Pure water at 25°C has a pH of
(1) 1 (2) 5 • (3) 7
(4) 14

The amount of heat released when 75 g of CH4O reacts is -1705.64 kJ.

The equation given is the balanced equation for the combustion of methanol (CH4O) with oxygen to form carbon dioxide (CO2) and water (H20). The value of ΔΗ given (-726 kJ) is the enthalpy change for the reaction, which represents the amount of heat released or absorbed when the reaction occurs.

To calculate the amount of heat released when 75 g of CH4O reacts, we need to use the equation: q = n x ΔΗ where,

We know that the molar mass of CH4O is 32.04 g/mol, so we can convert 75 g to moles using the following formula: n = m/M where,

So, n = 75 / 32.04 = 2.34 moles

Using this value of n in the equation above, we can calculate the heat released as q = 2.34 x -726 = -1705.64 kJ

Therefore, -1705.64 kJ of heat is released when 75 g of CH4O reacts.

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Answer:

Option A, light energy from the sun

Explanation:

In the process of photosynthesis, the energy from sun in the form of light and heat is taken to undergo glycolysis and prepare glucose/starch (chemical).  

Thus, the light and heat energy of sun is converted into the chemical energy.  

Option B and C are incorrect because no kinetic energy or chemical energy is taken from any source.  

Option D is also incorrect because heat is taken but it is not taken from the surrounding environment. The source of heat energy is sun.  

Thus, only option A is correct

The molarity of KOH solution  will be 0.75 M.

The amount of moles of solute per liter of solution is known as molarity (M). Molarity is defined as moles of solute per liter of solution. To ascertain the concentration of an identified analyte, titration is a typical laboratory technique for quantitative chemical analysis. A standard solution with a known concentration and volume is prepared as the reagent, also known as the titrant or titrator.

The balanced equation is

[tex]H_{2} SO_{4}[/tex]+ 2KOH = [tex]2H_{2} O[/tex]+  [tex]K_{2} SO_{4}[/tex]

2.50 x [tex]10^{-2}[/tex] M= [tex]\frac{x}{0.2 L}[/tex]

So, 0.75 M KOH.

So, The molarity of KOH solution  will be 0.75 M.

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Heterogeneous and homogeneous mixtures are the two types of mixtures.

When compared to homogeneous mixtures, heterogeneous mixtures can be visually divided into individual components. The most prevalent kind of homogeneous mixture is a solution, which can be a solid, liquid, or gas.

Solid, liquid, or gaseous homogeneous mixtures can exist. They are uniform in both appearance and chemical make-up. Water, air, steel, detergent, saltwater mixture, and other substances are examples of homogeneous mixtures. When two or more metals are combined in a specified proportion, an alloy is created.

A combination is said to be heterogeneous if its composition is not constant throughout. Vegetable soup is a complex concoction.

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Ethylene C2H2 , ascorbic acid formula C₆H₈O₆, naphthalene Chemical formula C₁₀H₈.

The relative ratios of the various atoms in a compound are given by an empirical formula. The ratios are still valid at the molar level. H 2 O is made up of two hydrogen atoms and one oxygen atom. Similar to this, 1.0 mole of H2O is made up of 1.0 mole of oxygen and 2.0 moles of hydrogen.

Originally known as hexuronic acid, ascorbic acid is an organic molecule having the formula C 6H 8O 6. Although impure samples may appear yellowish, it is a white solid. Water readily dissolves it, resulting in moderately acidic solutions. It is a gentle reducer.

There are two enantiomers (mirror-image isomers) of ascorbic acid, generally referred to as "l" (for "levo") and "d." (for "dextro"). The most prevalent isomer is the l one, which is a naturally occurring form of vitamin C (also known as a "vitamer") and is necessary for both humans and many other animals to survive. Scurvy is caused by vitamin C deficiency and used to be a serious condition affecting sailors on lengthy sea trips. Due to its antioxidant qualities, it is utilized as a nutritional supplement and food additive.

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a) The change in concentration of each reactant and product as a function of reaction rate is − Δ[H₂]/Δt = -Δ[I₂]/Δt = +1/2Δ[HI]/Δt.

b) The rate as to how fast is [HI] decreasing is 4 mol/[tex]L^{-s}[/tex].

A chemical reaction is the process by which a single or more reactants change into a single or more new products. Chemical building blocks or compounds make up substances.

Given balance chemical reaction,

H₂(g) + I₂(g) → 2HI(g)

a) The rate of reaction in terms of the change in concentration of each reactants & products is

Rate = − Δ[H₂]/Δt = -Δ[I₂]/Δt = +1/2Δ[HI]/Δt

b)  where 2, 1, 1 and stoichiometric coefficients of HI, H₂ and I₂ respectively.

where - sign indicates consumption and + ve sign indicates formation

given d[I₂]/dt =2

-d[HI]/2dt= 2

-d[HI]/dt = 4 mol/[tex]L^{-s}[/tex].

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The gas in a 250.0 mL piston experiences a change in pressure from 1.00 atm to 4.90 atm. 56.2 ml is the new volume (in mL) assuming the moles of gas and temperature are held constant.

Boyle's law states that at a given temperature, the volume of a gas and its pressure are inversely proportional.

Robert A. Boyle discovered the law in 1662, which states that at a constant temperature, the volume of a gas is inversely proportional to the pressure exerted by the gas.

Given:

Initial volume (V₁) = 250 mL

Initial pressure (P₁) = 1.00 atm

Final volume (V₂) = ?

Final pressure (P₂) = 4.45 atm

Assuming the gas has an ideal behavior, we can find the final volume by using Boyle's law as follows:

P₁ × V₁ = P₂ × V₂

V₂ = P₁ × V₁/P₂

V₂ = 1.00 atm × 250 mL / 4.45 atm

V₂ = 56.2 ml

Thus, 56.2 ml  is the new volume (in mL) assuming the moles of gas and temperature are held constant.

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The process of forcing liquid at high pressure into rocks, deep holes in the ground, etc. in order to force open existing cracks and take out oil or gas.

ANSWER :-

❥Fracking..!!!

Fracking is the process of drilling down into the earth before a high-pressure water mixture is directed at the rock to release the gas inside.

Hope it helps ya!❤

Answer:

Explanation:

A. Periodic table is beautifully arranged to place elements with similar chemical properties together. A family or a group is a vertical column in periodic table that has elements with similar property.

B. They all have similar properties because they all have the same number of valence electrons that determine the chemical properties such as reactivity of the element.

C. Lithium, sodium, potassium all fall in group 1 called alkali metals and these elements all share the property of being some of the most reactive elements.

(A) Vol. of solvent is 119.8 ml, (B) Molarity (M) of sol. is 5.00 M, (C) V1 of copper nitrate solution is 187.5 ml, (D) The instruction given is false.  

(A). To calculate the volume (ml) of a 2.25 M potassium hydroxide solution that contains 15.0 g of solute, we can use the formula:

The unit of measurement for molarity (M) is moles of solute per liter of solvent.

Rearranging the formula to solve for liters of solvent:

Molecularity = moles of solute / liters of solvent (M)

We know that the molar mass of potassium hydroxide (KOH) is 56.1 g/mol. To find the moles of solute, we can divide the given mass (15.0 g) by the molar mass of KOH:

15.0 g / 56.1 g/mol = 0.2679 moles

Now we can plug this value into the formula above:

Liters of solvent = 0.2679 moles / 2.25 M

Liters of solvent = 0.1198 L or 119.8 ml (rounded to 3 significant figures)

(B). To calculate the molarity of a solution containing 1.25 moles of glucose in 250. ml of solvent, we can use the formula:

The unit of measurement for molarity (M) is moles of solute per liter of solvent.

Plugging in the given values:

Molarity (M) = 1.25 moles / 0.250 L

Molarity (M) = 5.00 M

(C). To calculate the volume of a 10.00 M copper(II) nitrate solution that must be added to water to prepare 750.0 ml of a 2.500 M solution, we can use the formula:

M1V1 = M2V2

Where M1 and V1 are the concentration and volume of the original solution, and M2 and V2 are the concentration and volume of the final solution.

We know that the final solution has a volume of 750.0 ml and a concentration of 2.500 M, so we can plug in these values for V2 and M2:

M1V1 = 2.500 M x 750.0 ml

Now we can solve for V1 (the original volume) by rearranging the formula:

V1 = M2V2 / M1

V1 = (2.500 M x 750.0 ml) / 10.00 M

V1 = 187.5 ml (rounded to 4 significant figures)

(D). The instructions "Take 100.0 mL of the 10.0 M solution and add 900.0 mL water" are not correct for diluting a 10.0 M solution to a 1.00 M solution.

To achieve this dilution, you would need to take a smaller volume of the 10.0 M solution and add a larger volume of water, because the final volume should be larger than the starting volume.

For example, you could take 10.0 mL of the 10.0 M solution and add 90.0 mL of water, which would give you a final volume of 100.0 mL and a concentration of 1.00 M. The instruction given above is false.

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Answer:

7.01 hope this is right !

Explanation:

This problem can be summarized thusly:

qlost by copper = qgained by water + qgained by calorimeter

2) Therefore:

(610. g) (95.3 °C − x) (0.387 J g¯1 K¯1) = (45.0 g) (x − 36.5 °C) (4.184 J g¯1 °C¯1) + [(10.0 J/K) (x − 36.5 °C)]

Comment: The K and the °C cancel because the °C in this problem is a temperature difference (not one single specific value) and the "size" of one K = one °C.

22497.471 − 236.07x = 198.28x − 7237.22

424.35x = 29734.691

x = 70.1 °C

The ions will combine to form a salt are Cl- and Cs+ when Hydrochloric acid (HCl) is combined with cesium hydroxide (CsOH) in a neutralization reaction.

HCl + CsOH --> CsCl + H2O

Cesium chloride is the salt that results from the neutralization of hydrochloric acid with cesium hydroxide. Because both of the bonds in salt compounds the positively charged cesium ion and the negatively charged chloride ion have electrical charges, they are referred to as ionic bonds. A neutralization reaction occurs when an acid and a base combine to form salt and water in an aqueous solution. A salt is the name for the aqueous cesium chloride that is created during the process.

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Answer:

correct answer is 0.165 moles by calculation

It would be due to the scientific method

Hope this helps :)

There is 2.43 mg of ascorbic acid in the 5.00-mL sample, or 48.6 mg/100 mL of orange juice.

Explanation:

For i2+na2s2o3 titration,

I2 + 2 S2O3^-2 <--> 2 I^-1 + S4O6^-2

13.82 mL of 0.07203 M Na2S2O3 was needed to reach the starch indicator end point.

Number of moles of Na2S2O3 = 13.82*0.07203= 0.9954546 millimoles.

So, number of moles of excess I2 = 0.9954546/2 = 0.4977273 millimoles.

For oxidizing the ascorbic acid to dehydroascorbic acid

C6H8O6 + I2 --> C6H6O6 + 2 H+ + 2 I-

SO 1mole of I2 read for 1 mole of C6H8O6.

Initial I2 used = 50*0.01023 = 0.5115 millimoles.

Number of moles of I2 used = 0.5115 - 0.4977273 = 0.0137727 millimoles.

Number of moles of C6H8O6 in5 ml of orange juice = 0.0137727 millimoles.

Weight of C6H8O6 in5 ml of orange juice = number of moles * molecular weight = 0.0137727 * 176 = 2.4239952 mg

In 100 ml of orange juice = 2.4239952/5) *100 = 48.479904 milligrams per 100 mL. is the answer.

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The aforementioned claim is TRUE; as carbon-14 degrades steadily, it can be used to accurately estimate the age of rock samples.

The radioactive isotope of carbon 14 (14C) decays at a constant, well-known pace. Scientists can ascertain how long ago an organic substance died by calculating the quantity of 14C present in a sample of the material, such as bone or wood. This process, known as radiocarbon dating, is frequently used in geology and archaeology to date objects that are up to 50,000 years old.

Since carbon-14 decays steadily, it provides a trustworthy way to estimate the age of rock samples.

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Answer:

it can predict the properties of new elements, because it organizes the elements according to their atomic numbers.

Creating new elements is not a simple process. Scientists use a particle accelerator to smash light atoms into a thin metallic foil that contains heavier atoms. They hope that the two nuclei at the centre of these atoms will fuse and form a heavier nucleus.

When these heavy elements form, they are usually highly unstable. They decay so quickly that we don’t usually see the element itself. Instead, we see a decay product. In that respect, even new elements aren't always 'discovered' directly. In some cases, scientists haven’t synthesized enough of the element for us to know what the element even looks like! Nevertheless, we consider the elements as known. We name them and list them the periodic table.

For example, in 2003, scientists first observed element 115 (ununpentium, Uup) They bombarded americium-243 with calcium-248 ions and produced four atoms of Uup, which lived for less than one fifth of a second.

₂₀ ⁴⁸Ca + ₉₅²⁴³Am → ₁₁₅²⁸⁸Uup + 3 ₀¹n

It took until September 2013 for the discovery to be confirmed, and about 50 atoms have been synthesized to date.

We can predict the properties of Uup because the Periodic Table organizes elements according to their atomic number.

Answer:

The answer Is c. mole fraction of ethanol in water=0.50

Explanation:

Answer:

Explanation:

Pb(OH)2 + 2NaOH → Pb(OH)2 + 2NaOH

The balanced equation would be PbO + 2NaOH → Pb(OH)2 + Na2O

The reactant PbO is a lead oxide which is an acidic oxide, it reacts with NaOH, a strong base, to form Pb(OH)2, a lead hydroxide, which is a salt of lead, and Na2O which is sodium oxide , a base.

Answer:

Explanation:

the correct answer is A

Answer:

hey hope this work

The amount of bending depends on two things: Change in speed – if a substance causes the light to speed up or slow down more, it will refract (bend) more. Angle of the incident ray – if the light is entering the substance at a greater angle, the amount of refraction will also be more noticeable.

and the answer i think is A

Answer:

180 g

Explanation:

Answer:

Potassium was the first metal to be isolated by electrolysis. It was discovered by the  English chemist Sir Humphry Davy by decomposing molten potassium hydroxide (KOH) with a voltaic battery.

Explanation:

Potassium was discovered by the English chemist Sir Humphrey Davy.

Answer:

the third one is the one that you should pick

From 5.5 grammes of sodium fluoride, 4.1 grammes of magnesium fluoride will be created. The inorganic substance MgF2 stands for magnesium fluoride.

It naturally occurs as the rare mineral sellaite and is a white crystalline salt that is transparent over a broad range of wavelengths and has commercial use in optics used in space telescopes. With the formula NaF, sodium fluoride (NaF) is an inorganic substance. It is utilised in minute quantities in toothpaste, metallurgy, and as a flux in addition to fluoridating drinking water. It is a white or colourless substance that easily dissolves in water. Pharmaceutical manufacturers frequently use it as a source of fluoride. Mass in grammes is equal to 0.06548 times 62.301 grammes of MgF2.

= 0.06548 /62.301 = 4.1grams

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Answer:

Explanation:

25%

When a hydrogen atom is part of a molecular structure, it is always a terminal atom.

On the periodic table, hydrogen belongs to the group 1 element. Consequently, a hydrogen molecule contains two valence electrons. There are two identical atoms in the H2 molecule. As a result, any atom can be regarded as a centre atom. An atom attached to a central atom is referred to as a terminal atom if it is not H. Here are two illustrations of this differentiation. Add bonding electrons to the total number of electrons. The end of hydrogen will never come. The centre will often contain the least electronegative element. Since hydrogen can only have two electrons in its valence shell and hence can only make one bond, it can never be the centre atom.

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Answer:

C2H5OH + 3O2 → 2CO2 + 3H2O

Explanation: