# The answer to Chemical reaction

1 How many grams of oxygen are required to fill a 4.5 x 103 liter hyperbaric chamber at a pressure of 225 cm Hg and 62 F? If the same quantity of oxygen, was pumped back into a gas cylinder at a pressure of 200 atm and at 75 F, what would the volume be?

2 Any number of green plants can photosynthesize glucose (C6H12O6) in the presence of carbon dioxide and water, and producing oxygen as the remaining product. 250 ml of oxygen was produced. The oxygen was collected over water at 27C and at a pressure of 755 Torr. The vapor pressure of water at 27C is approximately 26mm Hg. What mass of glucose was produce? How many grams of water were used in this biosynthesis?

3 The solubility of laughing gas, dinitrogen monoxide, in water is 7.50 mg per cent by mass at 760 Torr and 25C. If the density of the resulting solution is 1.01 grams per milliliter, what is the morality of the resulting solution? What is the % of the volume?

4 The specific heat of fusion of silver is 25.0 calories per gram and the specific heat of silver is 0.25 Joules per gram per degree C. Calculate the energy required to melt 1.0 moles of silver if it starts as a solid at 25 C below its normal melting point and is heated to its normal melting point.

5 One of the methods for the determination of lead is the titration of lead solutions with a standardized potassium chromate solution. If 42.50 ml of a solution of 6.357 grams of potassium chromate per liter was used to completely react with a sample of 10.000 grams of a soluble lead salt, what is the percentage of lead in the sample?

6 To examine the soda fountain methods of making carbonated beverages by measuring the amount of acid in a fixed volume of Coca-Cola. Use a 250 ml sample for all analysis and make each batch with a separate CO2 cylinder so that the carbon dioxide content in each batch would be as uniform as possible. In a typical experiment, saturate the Coke solution with all the CO2 in the cylinder. Titrate the 250 ml sample of a phenolphthalein endpoint with 7.65 ml of a sodium hydroxide solution that contains 5.670 grams of sodium hydroxide per liter. How much carbon dioxide was in the saturated solution?

7 In the reaction of copper with concentrated nitric acid, the products are copper (II) nitrate, water and nitrogen monoxide, sometimes called nitric oxide. If 150 ml of nitric oxide were collected over mercury at 42C and under a pressure of 74.5 cm of mercury, how many grams of copper had reacted?

8 If all the nitric oxide from above problem was allowed to react with oxygen, a red-brow gas, nitrogen dioxide is formed. How many grams of nitrogen dioxide would be formed? How many oxygen molecules would be needed for this reaction?

9 Consider the carbon dioxide cylinder mentioned in problem 6 above. If the cylinder contains 27.35 grams of carbon dioxide, what volume would the gas occupy at 360 Torr and 850F?

10 Ammonia and gaseous hydrogen chloride combine to form ammonium chloride. If 4.21 liters of ammonia at 27C and 1.02 atm is combined with 5.35liters of hydrogen chloride at 26C and 0.998 atm, what mass of ammonium chloride will be produced? Which gas is in excess?

11 A tank contains 3.0 moles of nitrogen, 2.0 moles of oxygen, 1.5 moles of helium, and 1.8 moles of carbon dioxide at 45C and under 1000 atm. Calculate the partial pressure of each gas in the mixture in Torrcellis.

12 A weather balloon is filled with 1.0 liter of helium at 23C and 1.0 atm. What volume does the balloon have when it has risen to a point in the atmosphere where the pressure is 200 Torr and the temperature is -31C?

Unbalanced equation

CaCO3(s) + H+ (aq) Ca+2 (aq) + H2O(l) + CO2 (g)

How many moles of CO2 (g), are collected at 60C and 774 Torr, are produced by the complete reaction of 10.0 grams of CaCO3 with acid? What volume does this wet CO2 occupy? What volume would the CO2 occupy at 774 Torr if a desiccant, a chemical dying agent, were added to remove water? The vapor pressure of water at 60C is 149 mm Hg.

How many grams of silicon tetraflouride, a gas, at room temperature, would fill the same volume as the occupied by 295 grams of carbon monoxide at 75C and 575 Torr?

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#### Solution Preview

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1 How many grams of oxygen are required to fill a 4.5 x 103 liter hyperbaric chamber at a pressure of 225 cm Hg and 62° F? If the same quantity of oxygen, was pumped back into a gas cylinder at a pressure of 200 atm and at 75° F, what would the volume be?

PV = nRT

P = 225 cm Hg = 2250 mm Hg = (2250 mm Hg)(1 atm/760 mm Hg) = 2.96 atm

V = 4.5x10^3 L

R = 0.08206 L-atm/mol-K

T = 62° F = (62° F – 32°)/1.8 = 17° C = 290 K

Plug the numbers into the equation and solve for n, moles of oxygen.

n =PV/RT

Once you know moles, then use the molar mass of oxygen gas (32 g/mol) to convert moles into grams.

Then, to solve the next part, take that number of moles as n. R is the same. For T, convert 75° F to Kelvin as above. And for P, you’ve already got 200 atm. No need to modify that number. Plug numbers into this:

V = nRT/P

Your answer will be in litres.

2 Any number of green plants can photosynthesize glucose (C6H12O6) in the presence of carbon dioxide and water, and producing oxygen as the remaining product. 250 ml of oxygen was produced. The oxygen was collected over water at 27°C and at a pressure of 755 Torr. The vapor pressure of water at 27°C is approximately 26mm Hg. What mass of glucose was produce? How many grams of water were used in this biosynthesis?

To calculate the partial pressure of oxygen, P_O2 we must substract the vapor pressure of water since both pressures combined to give 755 torr. Therefore, the P_O2 was 755-26 = 720 mm Hg. Convert this into atm like this:

(720 mm Hg)(1 atm/760 mm Hg) = 0.947 atm

So, we know V = 0.250 L

P = 0.947 atm

R = 0.08206 L-atm/mol-K

T = 27 + 273 = 300 K

Plug the numbers into this equation and solve for n, moles of O_2 gas.

n =PV/RT

Now that we know moles of O_2 gas produced, we need to understand the balanced equation to find mass of glucose and moles of water.

CO_2 + H_2O → C_6H_1_2O_6 + O_2

Balance the equation.

6 CO_2 + 6 H_2O → C_6H_1_2O_6 + 6 O_2

Now to find mass of glucose produced, we know that for every 6 moles of O_2 produced, 1 mol of glucose is produced. Therefore, divide your moles of oxygen by 6 and you’ve got moles of glucose. Then, use the molar mass of glucose to get grams.

To find grams of water, do the same kind of calculation. You should be okay with that.

3 The solubility of laughing gas, dinitrogen monoxide, in water is 7.50 mg per cent by mass at 760 Torr and 25°C. If the density of the resulting solution is 1.01 grams per milliliter, what is the molarity of the resulting solution? What is the % of the volume?

1 mg % = 1 mg/100 g

Therefore, 7.50 mg % = 7.50 mg/100 g

or

0.00750 g/100 g

(0.00750 g)(1 mol/44 g) = 0.0001704 mol N2O in 100 g

The density of the solution is 1.01 g/mL.

Therefore, what is the volume of 100 g of the solution?

Set up a ratio, and you find out it is 99 mL.

Therefore, 0.0001704 mol / 0.099 L of H_2O = 0.0017 M

To find % volume, since we know the solution is 7.5 mg % by mass, just convert ...

#### Solution Summary

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Chemical Kinetics: Assessing Reactions

See the attached file.

1. Now consider the following reaction and data:

H 2 +2BrCl→2HCl+Br 2

Time (s)

Br 2 concentration (M)

5 1.35

15 1.65

Part A

What is the average rate of formation of Br 2 ?Express your answer to three decimal places and include the appropriate units.

2. Consider the reaction: A(g)+1 2 B(g)→2C(g) .

Part A

When C is increasing at a rate of 4.0×10−2M⋅s −1, how fast is B decreasing? Express your answer using two significant figures.

Part B

How fast is A decreasing? Express your answer using two significant figures.

3. Which of the following are correct for zero-order reactions? Check all that apply.

The rate of reaction does not equal the rate constant.

The units for the rate constant and the rate of reaction are the same.

A zero-order reaction slows down as the reaction proceeds.

A higher concentration of reactants will not speed up the reaction.

The concentration of the reactants changes nonlinearly.

4. In the hydrogenation of ethylene using a nickel catalyst, the initial concentration of ethylene is 1.90mol⋅L −1 and its rate constant (k) is 0.0013mol⋅L −1 ⋅s −1 . Determine the rate of reaction if it follows a zero-order reaction mechanism.Express your answer to two significant figures and include the appropriate units.

5. The rate of the reaction in terms of the "disappearance of reactant" includes the change in the concentration of the reactant, the time interval, and the coefficient of the reactant.

Consider the following reaction:

6. 2A+3B→3C+2D

The concentrations of reactant A at three different time intervals are given. Use the following data to determine the average rate of reaction in terms of the disappearance of reactant Abetween time = 0 sand time = 20 s .

Time (s )

0 20 40

[A](M)

0.0400 0.0240 0.0180

Express your answer in molar concentration per second to three significant figures.

7. The rate of the reaction in terms of the "appearance of product" includes the change in the concentration of the product, the time interval, and the coefficient of the product.

Consider the following reaction:

2A+3B→3C+2D

The concentrations of product C at three different time intervals are given. Use the following data to determine the rate of reaction in terms of the appearance of product C between time = 0 s and time = 20 s .

Time (s )

0 20 40

[C](M)

0.000 0.0240 0.0480

Express your answer in molar concentration per second to three significant figures.

8. Consider the following reaction:

NO+O 3 →NO 2 +O 2 , rate=k[NO][O 3 ]

Part A

What is the overall reaction order? Express your answer as an integer.

Part B

What are the units of the rate constant k for this reaction?

Part C

What would happen to the rate if [NO] were doubled?

Part D

9. What would happen to the rate if [O 3 ] were doubled? Consider the following elementary steps that make up the mechanism of a certain reaction:

1. 3A→B+C

2. B+2D→C+F

What is the overall reaction? Express your answer as a chemical equation.