the energy required to melt 40.3 g of ice at 0 oC.The molar heat of fusion for ice is 6.02 kJ/mol. the energy required to melt 40.3 g of ice at 0 oC is 13.5 kJ.
The energy required to melt a substance is given by the formula:
q = nΔH_fus
where q is the heat absorbed or released during the phase change, n is the number of moles of the substance undergoing the phase change, and ΔH_fus is the molar heat of fusion of the substance.
To apply this formula to the melting of 40.3 g of ice at 0 oC, we first need to calculate the number of moles of ice present:
moles of ice = mass of ice / molar mass of ice
moles of ice = 40.3 g / 18.015 g/mol
moles of ice = 2.235 mol
Next, we can use the formula for q to calculate the energy required to melt the ice:
q = nΔH_fus
q = 2.235 mol × 6.02 kJ/mol
q = 13.5 kJ
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During a lab experiment, 48.62 grams of magnesium reacted with 32.00 grams of oxygen to
produce magnesium oxide. What is the empirical formula for magnesium oxide?
(atomic masses: Mg = 24.31 and O = 15.99)
Along these lines, magnesium and oxygen should blend in a proportion of 1:1 to deliver magnesium oxide, which has the empirical formula MgO.
48 grams of magnesium will respond with what number of grams of oxygen?
80 grams of magnesium oxide are in this manner equivalent to 2 moles. Subsequently, 80 grams of magnesium oxide are made when 32 grams of oxygen and 48 grams of magnesium are consolidated.
We should initially distinguish the moles of magnesium and oxygen associated with the cycle to get the empirical formula for magnesium oxide:
Moles of Mg = 48.62 g/24.31 g/mol = 2.00 mol
Moles of O = 32.00 g/15.99 g/mol = 2.00 mol
The proportion of magnesium to oxygen in the response should not be entirely set in stone. By separating the absolute number of moles of every component by the lesser number of moles (in this model, 2.00 mol), we might achieve the accompanying:
Mg: 2.00 mol/2.00 mol = 1
O: 2.00 mol/2.00 mol = 1
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Consider the dissolution of NaBr and NaI. The values provided here will be helpful for answering the following questions.
ΔH∘soln (kJ/mol) ΔS∘soln Jmol•K
NaBr –0.860 57.0
NaI –7.50 74.0
a.Write a balanced equilibrium equation for the dissolution of NaI in water. Include phases.
b. Calculate the change in free energy if 1.18 moles of NaI is dissolved in water at 25.0°C.
c. What is the dissolution of 1.00 mol of NaBr at 298.15 K?
The change in free energy for the dissolution of 1.00 mol of NaBr at 298.15 K is -2.35 kJ.
a. The balanced equilibrium equation for the dissolution of NaI in water is:
NaI(s) ⇌ Na+(aq) + I-(aq)
b. The change in free energy (ΔG) can be calculated using the equation:
ΔG = ΔH - TΔS
where ΔH is the enthalpy change, T is the temperature in Kelvin, and ΔS is the entropy change. Plugging in the values for NaI:
ΔG = (-7.50 kJ/mol) - (298.15 K)(74.0 J/mol•K) / 1000 J/kJ
ΔG = -9.52 kJ/mol
Multiplying by the number of moles dissolved:
ΔG = -9.52 kJ/mol x 1.18 mol = -11.24 kJ
Therefore, the change in free energy when 1.18 moles of NaI is dissolved in water at 25.0°C is -11.24 kJ.
c. The change in free energy for the dissolution of NaBr can be calculated using the same equation:
ΔG = ΔH - TΔS
Plugging in the values for NaBr:
ΔG = (-0.860 kJ/mol) - (298.15 K)(57.0 J/mol•K) / 1000 J/kJ
ΔG = -2.35 kJ/mol
Therefore, the change in free energy for the dissolution of 1.00 mol of NaBr at 298.15 K is -2.35 kJ.
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I need to know how to graph this
Answer:
bar graph
Explanation:
because of the fact that the data is shown in such a way that a line graph would not work, you need to graph the data for each individual time
A4
notebook
(d) Ionic bonds often have some covalent character. This is influenced by the sizes and
charges of the ions involved. State how these two factors must change, for positive
ions and then for negative ions, to increase the covalent character in an ionic bond.
(i) Positive ions:
[1]
(ii) Negative ions:
[1]
Positive ions must shrink and have a stronger positive charge in order to increase the covalent nature of an ionic connection. Smaller ions can approach negatively charged ions, increasing their attraction and increasing the likelihood that electrons will be transferred.
The attraction between the two ions is increased by a stronger positive charge on the ion, increasing the likelihood that electrons will be transferred.
Negative ions must expand and have a stronger negative charge in order to increase the covalent nature of an ionic connection. The electrical attraction between the two ions is lessened as a result of larger ions putting more space between themselves and the positive ions.
It is more difficult for the electrons to be entirely transferred from one ion to the other when the ion has a higher negative charge, which leads to some degree of electron sharing between the two ions.
Ionic bondsPositively charged ions and negatively charged ions can form ionic bonds, which are defined by the transfer of electrons from one ion to another.
These ionic bonds, however, can have a covalent nature, which means that the two ions share some electrons to some extent.
The sizes and charges of the ions involved have an impact on the covalent nature of an ionic bond.
A smaller size and a larger positive charge will increase the covalent nature of the binding when positive ions are present.
This is due to the fact that smaller ions are more attracted to one another since they can be brought closer to one another.
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Read the passage and answer the next two questions.
Two students want to model thermal equilibrium. For this experiment, they will be
observing what happens when they mix two samples of water at different
temperatures. The students use the following procedure for the experiment.
Experiment 1 exhibiting thermal equilibrium
Step 1: Fill beaker A with 100 mL water and heat it using a Bunsen burner until
the thermometer measures 50°C. Record data.
Step 2: Fill beaker B with 100 mL of water at 20°C. Record data.
Step 3: Transfer the water from beaker A into beaker B.
Step 4: Record the temperature of the combined water sample.
10.The final temperature of the combined water from beakers A and B is 35°C.
Describe what happened in terms of kinetic energy of the particles when samples
A and B were combined.
11. The experiment modeled how two substances with varying temperatures will eventually reach thermal equilibrium on a macroscopic scale. Which statement best supports thermal equilibrium on a microscopic scale?
A. Beaker A has molecules of higher kinetic energy. These molecules collide with molecules from beaker B and transfer some of their energy. Energy is transferred until the average potential energy of the molecules from both samples are the same.
B. The molecules in beaker A are warmer than in beaker B, but both beakers have the same kinetic energy. Mixing the samples reduces the number of collisions in the samples.
C. Beaker A has molecules of lower kinetic energy. These molecules collide with molecules from beaker B and absorb energy until the average kinetic energy of the molecules from both samples are the same.
When the samples A and B are combined, the Kinetic energy of the particles will increase and in the second experiment option (C) best describes the thermal equilibirum on a microscopic level.
What is kinetic energy?Kinetic energy, which may be seen in the movement of an item or subatomic particle, is the energy of motion. Kinetic energy is present in every particle and moving object. Kinetic energy is a type of power that a moving object or particle possesses. An item accumulates kinetic energy when work, which involves the transfer of energy, is done on it by exerting a net force. A moving object or particle has kinetic energy, which depends on both its mass and its rate of motion. The type of motion can be vibration, rotation on an axis, translation (or travel along a path from one place to another), or any combination of these.
A body's translational kinetic energy, or 1/2mv², is determined by multiplying its mass, m, by the square of its velocity, v.
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Answer:
When samples A and B were combined, the kinetic energy of the particles transferred from the particles with higher kinetic energy (from beaker A) to the particles with lower kinetic energy (from beaker B). This transfer of kinetic energy resulted in the particles in the combined water sample having a new, average temperature of 35°C.
Explanation :
The statement that best supports thermal equilibrium on a microscopic scale is: A. Beaker A has molecules of higher kinetic energy. These molecules collide with molecules from beaker B and transfer some of their energy. Energy is transferred until the average potential energy of the molecules from both samples are the same. This statement explains how the transfer of kinetic energy occurs between the molecules in beakers A and B, resulting in the eventual thermal equilibrium of the combined water sample.
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Which are the factors that favor SN2 reactions, as described during the lab lecture?
a) Strong nucleophile, good leaving group, polar protic solver, methyl or primary halide. b) Strong nucleophile, good leaving group, polar aprotic solver, methyl or primary halide. c) Weak nucleophile, good leaving group, polar aprotic solver, methyl or primary halide. d) Strong nucleophile, poor leaving group, polar aprotic solver, tertiary halide. e) Strong nucleophile, good leaving group, polar aprotic solver, tertiary halide.
The SN2 reaction involves the strong nucleophile, good leaving group, polar aprotic solver, methyl or primary halide. So, option (b) is correct.
The SN2 reaction is defined as a type of reaction mechanism that involves one bond is broken and one bond is formed in a concerted way, that is in one step. This mechanism involves the nucleophilic substitution reaction of the leaving group that consists of halide groups or other electron-withdrawing groups with a nucleophile in a given organic compound.
The nucleophile attacks the carbon atom to which the leaving group is attached when the leaving group departs from the molecule. This reaction proceeds in a single step with the nucleophile and leaving group involved in the transition state.
Methyl halides are used in this reaction because they are less hindered which makes the attack by the nucleophile easier.
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the chemical formula for glucose is c6h12o6. what is the percent mass of hydrogen in glucose?
Answer:
6.67%
Explanation:
% by mass of hydrogen = mass of hydrogen/ total mass of the compound × 100%
mass of hydrogen = 1 × 12
= 12 g
total mass of compound = 12×6 + 1×12 +16×6
= 180 g
Therefore, % by mass of hydrogen = 12/180 × 100%
= 6.67%
Ca + 2H2O → Ca(OH)2 + H2.
How many moles of H2O are needed to exactly react with 2. 0 moles of Ca?
To create one mole of H₂, 2.0 moles of Ca must be reacted with 4.0 moles of water.
From the balanced chemical equation:
Ca + 2H₂O → Ca(OH)₂ + H₂
we can see that 1 mole of Ca reacts with 2 moles of H₂O to produce 1 mole of H₂. Therefore, we need to calculate how many moles of H₂O are required to react with 2.0 moles of Ca.
If 1 mole of Ca reacts with 2 moles of H₂O, then 2.0 moles of Ca will react with:
2.0 moles Ca x (2 moles H₂O/1 mole Ca) = 4.0 moles H₂O
Therefore, 4.0 moles of H₂O are needed to react with 2.0 moles of Ca to produce 1 mole of H₂.
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e) Give two uses of hydrogen gas.
Hydrogen can be used in fuel cells to generate electricity, or power and heat. Today, hydrogen is most commonly used in petroleum refining and fertilizer production, while transportation and utilities are emerging markets.
Superheated steam at T 1 ( ° C ) T1(°C) and 20. 0 bar is blended with saturated steam at T 2 ( ° C ) T2(°C) and 10. 0 bar in a ratio (1. 96 kg of steam at 20 bar)/(1. 0 kg of steam at 10 bar). The product stream is at 250°C and 10. 0 bar. The process operates at steady state. Calculate T 1 T1 and T 2 T2, assuming that the blender operates adiabatically. If in fact heat is being lost from the blender to the surroundings, is your estimate of T 1 T1 too high or too low? Briefly explain
To solve this problem, we can use the conservation of mass and energy principles. The mass balance equation can be written as:
1.96 kg steam at 20 bar = x kg steam at T₁ and 20 bar + (1-x) kg steam at T₂ and 10 bar
Solving for x gives:
x = 0.9014
Therefore, 0.9014 kg of the total steam mass comes from the superheated steam stream, while the remaining 0.0986 kg comes from the saturated steam stream.
The energy balance equation can be written as:
(1.96 kg)(h₁) = (0.9014 kg)(h₁) + (0.0986 kg)(hf₂) + (product stream)
Solving for h₁, we get:
h₁ = 3449 kJ/kg
Similarly, solving for T₂ using the saturation table for steam at 10 bar gives:
T₂ = 179.9°C
To find T₁, we can use the steam tables to look up the enthalpy of superheated steam at 20 bar and use the energy balance equation to solve for T₁:
(1.96 kg)(3188 kJ/kg) = (0.9014 kg)(3449 kJ/kg) + (0.0986 kg)(hf(T₂)) + (product stream)
Solving for T₁ gives:
T₁ = 511.6°C
If heat is being lost from the blender to the surroundings, our estimate of T₁ would be too high. This is because if the system is losing heat, the energy balance equation would be incorrect since it assumes that all the energy input is used to heat up the steam. Thus, T₁ would be overestimated, and the actual value would be lower.
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Compound x is a ketone that was treated with two equivalents of a thioacetal (in the presence of an acid) to form a thioacetal. the thioacetal was then treated with raney nickel to form diphenylmethane. identify the structure of compound x.
Compound x can be identified as a ketone containing a carbonyl group,
Let's start by breaking down the reaction:
Compound x (ketone) + 2 thioacetal + acid → thioacetal (product)
Thioacetal (product) + Raney nickel → diphenylmethane
In the first step of the reaction, the ketone (compound x) reacts with two equivalents of thioacetal in the presence of an acid to form the thioacetal product.
The thioacetal product is then treated with Raney nickel in the second step to form diphenylmethane.
Based on the reaction, we can infer that the carbonyl group of a ketone is replaced by a thioacetal group (-S-CH2-) when it reacts with two equivalents of thioacetal in the presence of an acid. The resulting product then undergoes hydrogenation with Raney nickel to form diphenylmethane.
Therefore, Compound x can be identified as a ketone containing a carbonyl group, but without any other functional groups that may interfere with this reaction. Without additional information or data, it is impossible to identify the specific structure of Compound x.
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A compound with the molar mass 32 g/mol has an empirical formula of NH2.what is the molecular formula of the compound
The molecular formula of the compound is [tex]NH_4[/tex] ammonium.
The empirical formula is the simplest ratio of atoms of each element in a compound, expressed as a whole number. To determine the molecular formula, we need to multiply the number of atoms in the empirical formula by the molar mass of the compound.In this case, the empirical formula is [tex]NH_2[/tex], meaning that there is one nitrogen and two hydrogen atoms. The chemical has a 32 g/mol molar mass.Therefore, if we multiply the number of atoms in the empirical formula by 32 g/mol, we will get the molecular formula, which is [tex]NH_4[/tex], meaning that there are four nitrogen and eight hydrogen atoms.
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Write a chemical equation for rusting of iron.
Best answer will be marked as brainliest :)
Answer:
I suppose it's 4Fe + 3O2 + 6H2O → 4Fe(OH)3
Explanation:
Iron needs both water and oxygen to oxidise and rust
Greek numerical prefixes are used to indicate the number of atoms of a particular element present in a molecular compound. Four atoms of the same element will be named with the prefix ___ , while the prefix ___ is used to indicate two atoms of the same element.
Greek numerical prefixes are used to indicate the number of atoms of a particular element present in a molecular compound. Four atoms of the same element will be named with the prefix "tetra-" while the prefix "di-" is used to indicate two atoms of the same element.
A prefix is a term added to the beginning of a word to alter its meaning. In chemistry, we often use prefixes to name molecular compounds. In particular, we use Greek numerical prefixes to indicate the number of atoms of a particular element present in a molecular compound.
Greek numerical prefixes are useful when naming complex molecular compounds because they provide an easy way to indicate how many atoms of a particular element are present in a compound. By using these prefixes, we can avoid writing out long chemical names that would be difficult to remember or pronounce.
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a solution made from ethanol (c2h5oh) and water is 2.68 m. how much c2h5oh is contained per 297 g of water?
The solution contains 2.68 m (mol/L) of C2H5OH (ethanol) per 297 g (mL) of water. To calculate the amount of C2H5OH (ethanol) contained per 297 g of water, you need to use the molar mass of C2H5OH (ethanol). The molar mass of C2H5OH is 46 g/mol.
Therefore, the amount of C2H5OH (ethanol) contained in 297 g (mL) of water is:
2.68 m (mol/L) x 46 g/mol = 123.28 g/L (or 123.28 g/mL)
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Determine if the following statements are true and false. Type true or false in the space provided.
Part A
To rinse the entire inner surface of the buret, one should add water from a wash bottle while rotating the buret.
Part B
Rinsing the buret with water is always enough to clean the buret.
Part C
To clean the inner surface of the buret, one should wash it with soapy water three times .
Part D
After rinsing with water and soapy water solution, one can add the titrating solution and begin the titration.
Part E
Always rinse a buret with the titration solution three times before beginning a titration.
The following statements are true or false:
A- To rinse the entire inner surface of the buret, one should add water from a wash bottle while rotating the buret. - True
B- Rinsing the buret with water is always enough to clean the buret. - False
C- To clean the inner surface of the buret, one should wash it with soapy water three times. - False
D- After rinsing with water and soapy water solution, one can add the titrating solution and begin the titration. - True
E- Always rinse a buret with the titration solution three times before beginning a titration. - False
To rinse the entire inner surface of the buret, one should add water from a wash bottle while rotating the buret. After using the buret, it is essential to clean it by rinsing it thoroughly. To do this, add water to the buret with a wash bottle while rotating it. This ensures that the whole inner surface of the buret is rinsed, which eliminates any residual substances.
Rinsing the buret with water is not always enough to clean the buret. While rinsing the buret with water is a crucial step in cleaning it, it is not always sufficient. Burets must be washed with soapy water to ensure that they are clean.
To clean the inner surface of the buret, one should not wash it with soapy water three times. Rather, the buret should be washed with soapy water once. The buret should be washed with a mild soap solution and then rinsed with water.
After rinsing with water and a soapy water solution, one can add the titrating solution and begin the titration. After cleaning the buret, the next step is to fill it with the titrating solution and begin the titration process.
One should not always rinse a buret with the titration solution three times before beginning a titration. After cleaning the buret, it should be rinsed thoroughly with water and not the titration solution. The titration solution should be added only when the buret is clean and ready for use.
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how many grams of Fe will be produced if 39.64 grams of CO2 are used?
If 39.64 grams of carbon oxide [tex]CO2[/tex] are used, the amount of Fe produced is 33.6 grams.
The production of iron (Fe) from carbon monoxide (CO) is typically represented by the following equation:
Fe2O3 + 3CO → 2Fe + 3CO2
From the balanced chemical equation, we can see that for every 3 moles of carbon oxide [tex]CO2[/tex], 2 moles of iron Fe are produced. We can use this relationship to calculate the amount of Fe produced from the given amount of carbon oxide.
First, we need to determine the number of moles of carbon oxidein 39.64 grams of carbon oxide. The molar mass of [tex]CO2[/tex]is 44.01 g/mol, so:
39.64 g carbon oxide× (1 mol carbon oxide/ 44.01 g carbon oxide) = 0.9018 mol [tex]CO2[/tex]
Next, we can use the mole ratio from the balanced equation to determine the number of moles of iron Fe produced:
(2 mol Fe / 3 mol carbon oxide) × 0.9018 mol carbon oxide= 0.6012 mol iron Fe
Finally, we can convert the number of moles of iron Fe to grams using the molar mass of Fe, which is 55.85 g/mol:
0.6012 mol iron Fe × (55.85 g Fe / 1 mol Fe) = 33.6 g Fe
Therefore, if 39.64 grams of carbon oxide are used, the amount of iron Fe produced is 33.6 grams.
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According to the collision theory, when can a chemical reaction occur?
A. When enough activation energy is added to correct the orientation of the particle collisions
B. When reactants collide with enough energy to intersect their valence shells and form new bonds
C. When reactants collide with enough mass to form new bonds and break apart the reactants
D. When the proper catalyst is added to break the chemical bonds in the reactants.
Answer: B. When reactants collide with enough energy to intersect their valence shells and form new bonds.
14) How much solute should be dissolved in 50 mL of water at 50 degrees
to make a saturated solution?
Answer:
250 grams
Explanation:
so if you look at the temperature of 50 and go up from there and stop at the red line you should get 250 grams, not positive but 99% of me says yes.
Wind energy is dependent on which factor?
Answer:
on it iis renewable energy it is independent
a solute with a mass of 76.4 g needs to be dissolved in water to make a solution with a 4.24% mass fraction. how much water is needed?
1804.7 g of water is needed achieve 4.24% mass fraction.
To make a solution with a mass fraction of 4.24 %, we need to dissolve 76.4 g of the solute in an appropriate amount of water.
To calculate the amount of water needed, use the following equation:
Mass fraction (%) = (Mass of solute / Mass of solution) x 100
Therefore, Mass of solution = (Mass of solute x 100) / Mass fraction (%)
Plugging in the given values,
we get: Mass of solution = (76.4 g x 100) / 4.24 = 1801.88 g
This means that 1804.7 g of water is needed to make a solution with a 4.24% mass fraction, using 76.4 g of the solute.
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what could have caused births to increase in the moon jelly population?
Moon jellyfish population births could increase as a result of environmental factors such as temperature, nutrient availability, food availability, etc.
The moon jellyfish is a marine species that belongs to the genus Aurelia. Moon jellies are very common and can be found in oceans worldwide. They have a life cycle that includes both asexual and sexual reproduction, which can cause their population to fluctuate.
Moon jellies are affected by various environmental factors, such as temperature and nutrient levels, which can affect their reproduction. Moon jellyfish population growth factors.
Moon jellyfish reproduction can be affected by a variety of environmental factors, including temperature, salinity, nutrient availability, and food availability. Moon jellies are also capable of asexual reproduction, which allows them to reproduce quickly in ideal conditions. This can lead to population increases.
The population of moon jellies may have increased as a result of climate change. The warming of the oceans might have led to a surge in moon jellyfish numbers.
Since jellyfish have a simple structure, they are well adapted to live in warm water. A lack of natural predators, as well as pollution and overfishing, could have also contributed to the population growth of moon jellyfish.
However, more research is needed to determine the specific factors that caused the moon jelly population to increase. Warming oceans might have led to a surge in moon jellyfish numbers.
Moon jellyfish populations might be affected by the lack of natural predators, pollution, and overfishing. However, more research is needed to determine the specific factors that caused the moon jelly population to increase.
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Move your mouse cursor over the hydrochloric acid (HCl) and sodium hydroxide(NaOH) on the Materials shelf. You will see that the concentration of the sodium hydroxide is known to be 0.1 M while the concentration of hydrochloric acid is unknown.
Take a burette from the Containers shelf and place it on the workbench.
Add 50 mL of sodium hydroxide (NaOH) titrant. (50 mL is the capacity of a burette). Notice that it doesn't fill completely to the top mark. This is because there is space in the burette below the bottom mark. In addition, this is NOT the volume in the burette but rather this is your INITIAL READING. In the wet lab, you would need to let some of the solution flow through the stopcock in order to assure that the NaOH solution completely filled the volume of the burette down to the tip. You don't have to do that here.
Note the buret reading as your initial NaOH volume (mL). You can double click on the buret and select show close up to view the volume more closely.
Take a clean Erlenmeyer flask from the Containers shelf and place it on the workbench.
Add 10 mL of hydrochloric acid(HCl), unknown concentration, to the Erlenmeyer flask. Record the volume of HCL (mL).
Add 10 mL of water to the Erlenmeyer flask. This increases the total volume in the flask, making it easier to see the color change, but note that the value to use for the volume of hydrochloric acid HCl when calculating its concentration is still 10 mL.
Add 2 drops of phenolphthalein solution to the Erlenmeyer flask.
Move the Erlenmeyer flask anywhere on the base of the burette. The Erlenmeyer flask is connected to the burette so that liquid will drip from the burette into the Erlenmeyer Flask.
Flow of the titrant from the burette is controlled by the black knob at the bottom of the burette glass tube. You can deliver one drop of titrant with each short click of the black knob, and you can deliver a stream of titrant from the burette by clicking-and-holding the black knob - the longer you hold the knob, the more titrant will be delivered all at once. Here is what the setup on your workbench should look like:
TitrationTutorialPic
You are now ready to start the first coarse titration. Try to find the length of time required to click and hold the burette knob so that you deliver approximately 2 mL of sodium hydroxide from the burette to the Erlenmeyer flask. After each click of the knob, move the mouse cursor over the burette – this will enable you to see its current volume. To determine the amount of titrant delivered from the beginning until now, subtract the amount of liquid currently in the burette from the starting volume.
Continue to add the sodium hydroxide titrant in 2 mL increments. Each time, note the burette volume level. Note when the end point is passed (when the color of your solution changes). You now know between which two readings the endpoint occurred. For example, if you recorded 32 mL before the end point, but 34 mL was past the endpoint, record the 32 mL as your FINAL NaOH (mL). Calculate the volume of titrant that was added when 32 mL were delivered (subtract your INITIAL NaOH (mL) reading). You know that the FINE TITRATION can begin after approximately that amount of titrant.
Remove the Erlenmeyer flask from the burette and place them both in the Recycle Bin.
Take a clean Erlenmeyer flask from the Containers shelf and place it on the workbench.
Add 10 mL of hydrochloric acid, 10 mL of Water and 2 drops of phenolphthalein to the Erlenmeyer flask.
Place the Erlenmeyer flask at the base of a new burette.
Add 50 mL of sodium hydroxide titrant to the burette.
Add the initial large quantity of titrant, determined performing the coarse titration, (which in the example in #10, was 16 mL) so that you can begin with the fine titration. The solution in the Erlenmeyer flask should still be colorless.
Add sodium hydroxide from the burette drop-wise. This means adding a single drop at time which is done with single, short clicks on the black knob. You may decide to click and hold for short times, but in doing so you may miss the exact endpoint of the titration.
When the solution in the Erlenmeyer flask changes color, stop adding titrant. Record FINAL NaOH (mL) reading. Calculate the NaOH Delivered (mL) by subtracting the initial reading from the final reading.
In theory, we would repeat at least two more FINE TITRATIONS with fresh samples of HCl and full burets. However, since this is just a tutorial, exit the lab once you have a copy of your data and go to the assignments to calculate the concentration of the hydrochloric acid (HCl).
when read the procedures for this experiment, you find that you will need two burets. what is the purpose of the second buret?
The second buret is a necessary component of this titration experiment as it allows you to accurately measure the amount of HCl needed to reach the endpoint. It is also necessary to accurately calculate the amount of NaOH delivered in the reaction.
The purpose of the second buret in this experiment is to measure the amount of hydrochloric acid (HCl) needed to reach the endpoint of the titration. This is necessary because the concentration of the hydrochloric acid is unknown. By using a second buret to measure the HCl, it allows you to accurately titrate the NaOH solution until the solution in the Erlenmeyer flask changes color, indicating the endpoint of the titration. This measurement also allows you to calculate the amount of NaOH delivered in the reaction. In order to use a second buret for the experiment, it should be filled with the HCl solution and placed above the Erlenmeyer flask. To start, you should open the valve at the top of the buret, allowing the HCl to begin to flow into the Erlenmeyer flask. Then, you should slowly add the HCl until the solution in the flask changes color, which indicates the endpoint of the titration. After that, you should record the FINAL HCl reading from the buret and calculate the HCl delivered (mL) by subtracting the initial reading from the final reading.
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what is not a characteristic of the halogen family?
The halogen family is a group of non-metallic elements located in group 17 or 7A of the periodic table. Some of the characteristics of the halogen family include:
They have a high electronegativity, meaning they tend to attract electrons towards themselves in chemical bonding.
They have a high electron affinity, meaning they tend to gain electrons in chemical reactions.
They are highly reactive and tend to form compounds with other elements, especially metals.
They exist in all three states of matter at room temperature, depending on the element. For example, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid.
They are diatomic molecules in their elemental form, meaning they exist as two atoms of the same element bonded together. For example, chlorine gas (Cl2) and fluorine gas (F2).
One characteristic that is not true of the halogen family is that they are good conductors of heat and electricity. In fact, they are poor conductors of heat and electricity, which is a common characteristic of non-metallic elements. Halogens are also not typically used as structural materials, as they tend to be brittle and have low melting and boiling points compared to metals.
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Explain 3 different ways that fossils can form? 30 points
Answer:
Fossils form in five ways: preservation of original remains, permineralization, molds and casts, replacement, and compression.
Explanation:
Rock formations with exceptional fossils are called very important for scientists to study. They allow us to see information about organisms that we may not otherwise ever know.
Fossils are formed in many different ways, but most are formed when a living organism (such as a plant or animal) dies and is quickly buried by sediment (such as mud, sand or volcanic ash). Soft tissues often decompose, leaving only the hard bones or shells behind (but in special circumstances the soft tissues of organisms can be preserved). After the organism has been buried, more sediment, volcanic ash or lava can build up over the top of the buried organism and eventually all the layers harden into rock
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The entire amount of greenhouse gases (such as carbon dioxide and methane) produced by human actions is known as a carbon footprint. One of the highest rates in the world, the average carbon footprint of a person in the United States is 16 tonnes.
What kinds of carbon footprint examples are there?As we drive, heat our homes with oil or gas, consume fuel for transportation, or use electricity produced from coal, natural gas, or oil, we all emit greenhouse gases.
Why is having a high carbon footprint bad?Described by the WHO as a weight of CO2, a carbon footprint is a measurement of the effect your actions have on the amount of carbon dioxide (CO2) created by the combustion of fossil fuels.
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Calculate the final volume of a system that absorbs 0. 86 KJ of energy if at a constant pressure of 2. 5 atm if its internal energy is 970 J and its initial volume is 1. 5 litres. Give your answer without units in two decimal points
1.20 L is the system's total volume.
The first law of thermodynamics states that the change in internal energy (ΔU) of a system is equal to the heat added (Q) to the system minus the work (W) done by the system, or ΔU = Q - W. Assuming that the only work done by the system is pressure-volume work, we can write this as ΔU = Q - PΔV, where P is the constant pressure and ΔV is the change in volume.
Solving for ΔV, we get ΔV = (Q - ΔU) / P. Substituting the given values, we get ΔV = (0.86 KJ - 970 J) / (2.5 atm) = -0.299 L.
The negative sign indicates that the volume of the system has decreased. To find the final volume, we can subtract ΔV from the initial volume: Vf = Vi + ΔV = 1.5 L - 0.299 L = 1.20 L.
Therefore, the final volume of the system is 1.20 L (without units), rounded to two decimal points.
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if 39.99g naoh in 1 l of water is a 1 m solution what would the molarity be if 39.99g naoh was dissolved in 0.2 l water
The molarity of the NaOH solution when 39.99 g NaOH is dissolved in 0.2 L water is 4.999 M.
The molarity of the NaOH solution can be calculated using the formula
M = n/V,
where M is the molarity, n is the number of moles of solute, and V is the volume of the solution.
Here, we are given the mass of NaOH and the volume of the solution, so we need to first calculate the number of moles of NaOH present in the solution. The molar mass of NaOH is 40.00 g/mol (sodium: 22.99 g/mol, oxygen: 15.99 g/mol, hydrogen: 1.01 g/mol).
Thus, the number of moles of NaOH in 1 L of water is:
m = mass/molar mass = 39.99 g/40.00 g/mol = 0.9998 mol
NaOH has a molar mass of 40.00 g/mol.
The molarity of NaOH in the solution is:
Molarity (M) = n / V.0.9998 moles NaOH were dissolved in 1.0 L water.
Molarity = 0.9998 moles / 1.0 L = 0.9998 M
When 39.99 g NaOH was dissolved in 0.2 L water, the volume of the solution was less than the original volume. Thus, the molarity of the solution will be higher than 0.9998 M.
Let's calculate the moles of NaOH present in 39.99 g:
Mo = mass / molar mass = 39.99 g / 40.00 g/mol = 0.9998 mol
Molarity (M) = n / V.0.9998 moles NaOH were dissolved in 0.2 L water.
Molarity = 0.9998 moles / 0.2 L = 4.999 M
Therefore, the molarity of the NaOH solution when 39.99 g NaOH is dissolved in 0.2 L water is 4.999 M.
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The combustion of octane is expressed by the thermochemical
equation
CgH18 (1) + O₂(g) →8 CO₂(g) + 9 H₂O (1)
AH = -5471 kJ
Estimate the mass of octane that would need to be burned to
produce enough heat to raise the temperature of the air in a 12 ft X
12 ft X 8.0 ft room from 40.°F to 78°F on a mild winter's day. Use
the normal composition of air to determine its density and assume
a pressure of 1.00 atm.
68.7 grams
The first step is to calculate the volume of the room in cubic meters. 12 ft X 12 ft X 8.0 ft = 345.6 cubic feet. Converting cubic feet to cubic meters, we get 9.793 cubic meters.
Next, we need to calculate the mass of air in the room. The density of air at 1.00 atm and 25°C is approximately 1.2 kg/m³. Multiplying this density by the volume of the room, we get 11.752 kg of air.
To calculate the amount of heat needed to raise the temperature of the air from 40°F to 78°F, we need to know the specific heat capacity of air. The specific heat capacity of air at constant pressure is approximately 1.005 kJ/kgK.
The temperature difference is (78 - 40) = 38°F, which is equivalent to (38/1.8) = 21.1°C. Converting to Kelvin, we get (21.1 + 273.15) = 294.25 K.
Now we can calculate the amount of heat needed using the formula:
Q = mcΔT
where Q is the amount of heat needed, m is the mass of air, c is the specific heat capacity of air, and ΔT is the temperature difference.
Plugging in the values, we get:
Q = (11.752 kg) x (1.005 kJ/kgK) x (294.25 K - 25°C)
Q = 3,292 kJ
Finally, we can use the thermochemical equation to calculate the mass of octane needed to produce this amount of heat:
5471 kJ of heat is produced by the combustion of 1 mole of octane. Therefore, to produce 3292 kJ of heat, we need:
(3292 kJ) / (5471 kJ/mol) = 0.601 mol of octane
The molar mass of octane is approximately 114 g/mol. Therefore, the mass of octane needed is:
(0.601 mol) x (114 g/mol) = 68.7 g of octane
So, approximately 68.7 grams of octane would need to be burned to produce enough heat to raise the temperature of the air in a 12 ft X 12 ft X 8.0 ft room from 40°F to 78°F on a mild winter's day.
To generate enough heat to boost the air's temperature, about 68.7 grammes of octane would need to be burned.
Octane formula: What is it?With the chemical formula C8H18 and the condensed structural formula CH3(CH2)6CH3, octane is both an alkane and a hydrocarbon.
The room's cubic meterage must be determined in the first stage.
= 12 ft X 12 ft X 8.0 ft = 345.6 cubic feet.
= 9.793 cubic meters.
Next, we must determine the air mass in the space. At 1.00 atm and 25°C, air has a density of around 1.2 kg/m3.
By dividing this density by the room's volume, we arrive at 11.752 kg of air.
At constant pressure, the specific heat capacity of air is roughly 1.005 kJ/kgK.
The temperature difference is (78 - 40) = 38°F,
which is equivalent to (38/1.8) = 21.1°C
= (21.1 + 273.15) = 294.25 K
Now we can calculate the amount of heat needed using the formula:
Q = mcΔT
Plugging in the values, we get:
Q = (11.752 kg) x (1.005 kJ/kgK) x (294.25 K - 25°C)
Q = 3,292 kJ
5471 kJ of heat is produced by the combustion of 1 mole of octane. Therefore, to produce 3292 kJ of heat, we need:
(3292 kJ) / (5471 kJ/mol) = 0.601 mol of octane
The molar mass of octane is approximately 114 g/mol. Therefore, the mass of octane needed is:
(0.601 mol) x (114 g/mol) = 68.7 g of octane
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you used 1.494 g of your unknown weak acid and it took 36.04 ml of your standardized 0.111 m naoh to reach the 2nd equivalence point, using the procedure described in the lab manual. what is the molecular weight of the acid?
The molecular weight of the unknown weak acid is approximately 373.67 g/mol. To determine the molecular weight of the unknown weak acid, we'll first calculate the moles of NaOH used and then the moles of the acid, and finally use the given mass of the acid to find the molecular weight.
Follow these steps:
1. Convert the volume of NaOH to liters: 36.04 mL * (1 L / 1000 mL) = 0.03604 L
2. Calculate the moles of NaOH: moles = Molarity * Volume = 0.111 M * 0.03604 L = 0.00399844 mol
3. Since the NaOH and the weak acid react in a 1:1 ratio at the 2nd equivalence point, the moles of the weak acid will be equal to the moles of NaOH: moles of weak acid = 0.00399844 mol
4. Now, use the given mass of the weak acid (1.494 g) and the moles of the weak acid to calculate the molecular weight: Molecular weight = Mass / Moles = 1.494 g / 0.00399844 mol = 373.67 g/mol
Thus, the molecular weight of the unknown weak acid is approximately 373.67 g/mol.
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