Why do the fourth and fifth periods contain 18 elements rather than 8 as observed in the second and third periods?

Answer:

The heat at constant pressure is -3,275.7413 kJ

Explanation:

The combustion equation is 2C₆H₆ (l) + 15O₂ (g)  → 12CO₂ (g) + 6H₂O (l)

[tex]\Delta n_g[/tex] = (12 - 15)/2 = -3/2

We have;

[tex]\Delta H = \Delta U + \Delta n_g\cdot R\cdot T[/tex]

Where R and T are constant, and ΔU is given we can write the relationship as follows;

[tex]H = U + \Delta n_g\cdot R\cdot T[/tex]

Where;

H = The heat at constant pressure

U = The heat at constant volume = -3,272 kJ

[tex]\Delta n_g[/tex] = The change in the number of gas molecules per mole

R = The universal gas constant = 8.314 J/(mol·K)

T = The temperature = 300 K

Therefore, we get;

H = -3,272 kJ + (-3/2) mol ×8.314 J/(mol·K) ×300 K) × 1 kJ/(1000 J) = -3,275.7413 kJ

The heat at constant pressure, H = -3,275.7413 kJ.

Answer:

D.) 1.71 M NaCl

Explanation:

Molarity equation: M= n/v

n= moles of solute

v=liters of solution

NaCl= 58.443 g/mol

30g NaCl / 58.443g/mol = 0.5133(this is n)

0.5133 mols/0.300 L=1.71115674 M

Thermal energy increases before the water begins to boil.

Thermal energy is produced when the atoms and molecules in matter vibrate faster due to an increase in temperature. As the average kinetic energy of its particles increases, the thermal energy of the object increases.

After reaching water at its boiling point thermal energy remain same because temperature remain constant after reaching once at boiling point. Thermal energy is directly proportional to temperature. Hence, chef will notice two phenomena during water begins to boil.

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Chemical: Wear the proper personal protective equipment (PPE) such as gloves, goggles, and an apron or lab coat.

Chemistry is the scientific study of the composition, structure, properties, and reactions of matter, especially at the atomic and molecular levels.

Use the chemical in a well-ventilated area.

Follow safety instructions and product labeling instructions precisely.
Avoid breathing vapors or mists of the chemical.
Immediately wash hands and exposed skin thoroughly with soap and water after contact with the chemical.
Store the chemical in a secure location away from food, drink, and other materials.
Dispose of the chemical properly.

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A bleaching solution requires 6. 55 g of sodium hypochlorite. 30.47 grams of a 21. 5% by mass solution of sodium hypochlorite should be used

Mass of sodium hypochlorite = 6.55 g

percent composition = 21. 5%

This indicates that there are 21.5 grams of sodium hypochlorite present in every one hundred grams of solution.

Now calculate the number of grams of solution for 6.55 g of solution.

(6.55 g x 100) / 21.5 g = 30.47 g

Therefore, you will need 30.47 grams of a sodium hypochlorite solution that has a mass concentration of 21.5% in order to obtain 6.55 grams of sodium hypochlorite.

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Answer:

The empirical formula of ribose (a sugar) is CH2O. In a separate experiment, using a mass spectrometer, the molar mass of ribose was determined to be 150 g/mol.Explanation:

Answer:

The empirical formula of ribose (a sugar) is CH2O. In a separate experiment, using a mass spectrometer, the molar mass of ribose was determined to be 150 g/mol.

Explanation:

Answer:

the higher the kinetic energy

Explanation:

because their will be easy movement of particles.

Answer:

3.01×10²⁴ atoms

Explanation:

Our compound is the Na₃PO₄

Sodium phosphate.

We assume, we have 5 moles of the mentioned salt.

1 mol of anything contains 6.02×10²³ atoms.

That's the Avogadro's number. The conversion is:

5 mol . 6.02×10²³ atoms /1mol = 3.01×10²⁴ atoms

Thermal energy flow between a hot or cold pack and the atmosphere by the D. Hot packs absorb energy from the atmosphere and cold packs release energy into the atmosphere.

When a hot pack is applied to the skin, the heat energy stored inside the pack is transferred to the skin, by conduction, and the heat energy is absorbed by the skin. Cold packs work in the opposite way, the cold energy stored inside the pack is transferred to the skin and released into the atmosphere.

The heat energy is conducted out of the pack and then radiated out into the atmosphere in the case of a cold pack, and The heat energy is conducted into the pack and then radiated out into the atmosphere in the case of a hot pack.

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According to the stoichiometry of the given chemical equation 102.03 g of Al₂O₃ is formed from 54 g of aluminium.

It is the determination of proportions of elements or compounds in a chemical reaction. The related relations are based on law of conservation of mass and law of combining weights and volumes.

Stoichiometry is used in quantitative analysis for measuring concentrations of substances present in the sample. As per stoichiometry of the given chemical equation, 107.92 g aluminium gives 203.92 g Al₂O₃, thus 54 g aluminium will give 54×203.92/107.92=102.03 g.

Thus,  102.03 g of Al₂O₃ is formed from 54 g of aluminium.

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Answer:

The reaction is favorable at all temperatures

Explanation:

Since G = H - TS, -H and +S would result in G = -H -TS, which will always be negative.

Answer:

C. Theories have been confirmed through tests; hypotheses haven't.

Hope this helps!!

Aspartic acid and phenylalanine are the two amino acids that make up aspartame, along with methanol. When the body processes this third key ingredient, formaldehyde and formic acid are produced.

Materials, Raw Two amino acids, phenylalanine and aspartic acid, as well as methanol, make up aspartame. L-aspartyl-L-phenylalanine methyl ester is its formal chemical name. Proteins are made up of amino acids, which are frequently referred to as the building blocks of proteins. Aspartame has the chemical formula C14H18N2O5. In foods and beverages, aspartame, a synthetic, non-saccharide sweetener that is 200 times sweeter than sucrose, is frequently used as a sugar substitute. The commercial names for it are NutraSweet, Equal, and Canderel.

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The amide group in salicylamide is electron withdrawing, the hydroxyl group on the ring is a highly active, electron donating substituent. The hydroxyl group donates electrons, guided entry iodide to a para position.

A substituent is an atom that are substituted for an atom here on parent chain of such a hydrocarbon in both chemistry and biochemistry constituting a moiety of the resulting new molecule.

Alkyl groups are substitutes created from alkanes. The names of alkyl groups and unbranched alkane chains are similar. Alkyl groups may branch as well. For instance, the butyl substituent has three constitutional isomers.

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The proper IUPAC name for the compound is (2R,3S)-2,3-difluorohexane.

It is determined by following the IUPAC nomenclature rules for organic compounds. The key points for this are:

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Answer:

To find molarity we must convert grams KCl to moles KCl and mL solution to L: ... EXAMPLE: What mass of potassium chloride would be needed to prepare 250.0 mL of a 0.500 ... EXAMPLE: Silver nitrate solution is added to 25.00 mL of a 0.500 M potassium chloride ... g) 0.655 g of sodium carbonate in 100.0 mL of solution.

Explanation:

The isotopic mass of the least abundant isotope will be 123.05 u.

Average atomic mass of X = 122.131 u

Assume most abundant isotope = Y and least abundant isotope = Z

Relative abundance (Y) = 61.35%

So,

Z = 100 - 61.35

Z = 38.65 %

Isotopic mass of Y= 121.552 u

Isotopic mass of Z = ?

To calculate the isotopic mass we use the following formula:

Average atomic mass = [(mass Y × percent abundance) + (mass Z × percent abundance)] / 100

put the values

122.131 = [(121.552 × 61.35) + (Z × 38.65)] / 100

12213.1 = (7457.22) + (Z × 38.65)

Z × 38.65 = 12213.1 - 7457.22

Z × 38.65 = 4755.88

Z = 4755.88 / 38.65

Z = 123.05

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Answer:

because it has love with

Answer:

las plantas

Explanation:

Las plantas son los seres vivos capaces de transformar energía luminosa utilizando agua y dióxido de carbono (CO₂) en energía química en forma de moléculas llamadas carbohidratos. El proceso a través del cual realizan esto se denomina fotosíntesis, y para ello requieren un pigmento de color verde denominado clorofila, el cual es necesario para captar la energía luminosa proveniente del Sol.

Yes, magnesium is a metallic element and is a member of the alkaline earth metals group.

What is  Magnesium?

Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a silvery-white, highly reactive metal that is essential for many biological processes. Magnesium is the eighth most abundant element in the Earth's crust and the fourth most abundant element in the human body.

It is an important component of many enzymes, proteins, and other molecules. Magnesium is found naturally in many foods, including green vegetables, nuts, and grains. Magnesium plays a role in maintaining normal muscle and nerve function, keeping a healthy immune system, regulating blood sugar levels, and helping to form strong bones.

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According to  the concept of molar mass and stoichiometry, the  mass of copper(II) sulfate  that would remain after removing all the water from 55 g of CuSO₄ · 5 H₂O is 35.18 g.

Molar mass of a compound or a molecule is defined as the mass of the elements which are present in it.The molar mass is considered to be a bulk quantity not a molecular quantity. It is often an average of the of the masses at many instances.

Molar masses of an element are given as relative atomic masses while that of compounds is the sum of relative atomic masses which are present in the compound.

In copper(II) sulfate , 249.68 g of copper (II) sulfate has 90 g water, thus 55 g of copper (II) sulfate will have 55×90/249.68=19.82 g water, so mass of copper sulfate= 55-19.82=35.18 g copper(II) sulfate.

Thus,35.18 g copper(II) sulfate would remain after removing all the water from 55 g of CuSO₄ · 5 H₂O.

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Here, naphthalene is being burned in a water-filled bomb calorimeter.

What is Combustion?

Combustion is a chemical reaction between a fuel and an oxidizer in which heat, light, and other products of combustion are released. The most common type of combustion is the burning of hydrocarbon fuels, such as natural gas or gasoline, to produce carbon dioxide and water vapor as the main products.

Heat of combustion = [mass of water x specific heat capacity x (final temperature - initial temperature)] / (mass of naphthalene)

Heat of combustion = (650 g x 4.185 J/g∙°C x 6.4°C) / (0.5 g)

Heat of combustion = 16,914 J/g

Heat of combustion = 16,914 J/g x (1 mol/128 g)

Heat of combustion = 131.5 kJ/mol

Hence, the heat of combustion is 131.5 kJ/mol.

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In the chemical equation,Cl₂ (g) + K+ Br− → K+ Cl− + Br₂ (g) bromine looses an electron in the reaction.

Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.

The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.

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The ocean current is caused by differences in water density. The difference in the density of water is mainly caused by the temperature and salinity of water.

Density of a substance is the measure of its mass per unit volume. It describes how closely its particles are packed within a given volume. Density of a substance is dependent on the temperature and pressure also.

The density of water is affected by the temperature and salinity. Water has its maximum density at 4 ° C. The more saline is water, more will be the density. Because, more ions or salts makes water denser.

The density vary with variations in temperature and salinity. This variation causes water currents from the denser areas to the less dense areas. Ocean currents are also affected by the gravity.

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Complete question:

A spirit burner used 1.00 g methanol to raise the temperature of 100.0 g water in a metal can from 28.00C to 58.0C. Calculate the heat of combustion of methanol in kJ/mol.

Answer:

the heat of combustion of the methanol is 402.31 kJ/mol

Explanation:

Given;

mass of water, [tex]m_w[/tex] = 100 g

initial temperature of water, t₁ = 28 ⁰C

final temperature of water, t₂ = 58 ⁰C

specific heat capacity of water = 4.184 J/g⁰C

reacting mass of the methanol, m = 1.00 g

molecular mass of methanol = 32.04 g/mol

number of moles = 1 / 32.04

                             = 0.0312 mol

Apply the principle of conservation of energy;

[tex]n\Delta H_{methanol} = Q_{water}\\\\n\Delta H_{methanol} = mc\Delta t\\\\n\Delta H_{methanol} = 100 \times 4.184\times (58-28)\\\\n\Delta H_{methanol} = 12,552 \ J\\\\n\Delta H_{methanol} = 12.552 \ kJ\\\\\Delta H_{methanol} = \frac{12.552}{n} \\\\H_{methanol} = \frac{12.552 \ kJ}{0.0312 \ mol} \\\\\Delta H_{methanol} = 402.31 \ kJ/mol[/tex]

Therefore, the heat of combustion of the methanol is 402.31 kJ/mol

Answer:

Explanation:‎

The complete question is as follows: How many moles of a gas at 100 c does it take to fill a 1.00 l flask to a pressure of 152kPa

Answer: There are 0.0489 moles of a gas at [tex]100^{o}C[/tex] is required to fill a 1.00 l flask to a pressure of 152kPa.

Explanation:

Given: Volume = 1.00 L,    

Pressure = 152 kPa (1 kPa = 1000 Pa) = 152000 Pa

Convert Pa into atm as follows.

[tex]1 Pa = 9.86 \times 10^{-6} atm\\152000 Pa = 152000 \times \frac{9.86 \times 10^{-6}atm}{1 Pa}\\= 1.5 atm[/tex]

Temperature = [tex]100^{o}C = (100 + 273) K = 373 K[/tex]

Using the ideal gas formula as follows.

PV = nRT

where,

P = pressure

V = volume

n = no. of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

[tex]PV = nRT\\1.5 atm \times 1.0 L = n \times 0.0821 L atm/mol K \times 373 K\\n = \frac{1.5 atm \times 1.0 L}{0.0821 L atm/mol K \times 373 K}\\n = 0.0489 mol[/tex]

Thus, we can conclude that there are 0.0489 moles of a gas at [tex]100^{o}C[/tex] is required to fill a 1.00 l flask to a pressure of 152kPa.

Answer:

sp3d

Explanation:

The ground state electronic configuration of tin is written as; [Kr] 5s²4d¹⁰5p². Hybridization is a concept used to explain the combination of orbitals of appropriate energy to produce suitable orbitals that could be used for bonding.

In forming the compound Snf5^ -1, we have to hybridize the following orbitals on tin; 5p, 5d and 6s orbitals. This gives us a set of sp3d hybrid  hence the answer.