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"Activity - Stoichiometry Exercises"
1. 1a. How many atoms are in 12 molecules of glucose.
1a. How many atoms are in 12 molecules of glucose, C6H12O6 ?
Use exact value for this answer.
24

2. 1b. How many moles of fluorine gas (F<sub>2</sub> molecule)?
1b. How many moles of fluorine gas (F2 molecule) are present in 55.0 grams of fluorine (F2) ?
1.45

3. 1c. What is the mass (g) of a single molecule of CO<sub>2</sub>
1c. What is the mass (g) of a single molecule of CO2 ? Hint: Express your answer in terms of grams per molecule.

0.0000000000249 = 2.49 e -11
1.

4. 1d. What is the atomic mass (atomic weight, g/mol) of an element.
1d. What is the atomic mass (atomic weight, g/mol) of an element that weighs 9.12 x 10-23 g ?
1.

5. 1e. Mole and Avogadro's Number: C8H9O4
01e. What is the mass (grams) of 0.216 mol of C8H9O 4 ?
Round off to the tenth of a gram.
1.

6. 2a. Balancing Equation and the Mole Concept
2a. Balance the equation and determine the number of moles of potassium chlorate (KClO3) required if 6 moles of potassium chloride and 9 of oxygen is produced from its decomposition.
Type in the moles of potassium chlorate.
1.

7. 2b. Balancing Equation and the Mole Concept
2b. How many moles of H2O will be produced from the complete combustion of 4.4g of C3H8 ?

1.

8. 2c. Balancing Equation and the Mole Concept
2c. A sample of ammonium dichromate (NH4)2Cr2O7, contains 2.25 mol of hydrogen atoms. What is the number of moles of oxygen atom in the sample?
1.

9. 2d. Balancing Equation and the Mole Concept
2d. Balance the equation and determine the mass (grams) of nitrogen dioxide produce when 102.0 grams of ammonia reacts with excess oxygen to produce nitrogen dioxide and water.
1.

10. 3a. Mass of hydrogen

3a. Calculate the mass (grams) of hydrogen formed when 25.00 g of aluminum reacts with excess HCl. The other product from this reaction is aluminum chloride.
1.

11. 3b. Mass of ammonia
3b. Carbon dioxide, CO2, and ammonia, NH3, combines together to form urea, CH4N2O, plus water. Write a balanced equation and calculate the mass of ammonia in grams that would be needed to make 2.0 moles of urea.
Use two significant figures.
1.

12. 3c. Grams of oxygen
3c. How many grams of oxygen are required to burn the 14.4 g of C5 H12 ?
1.

13. 3d. Moles of oxygen
3d. How many moles of oxygen are needed to produce 11.0 g of P4 O6 from phosphorus
Round off to a thousandth of a mole.
1.

14. 3e. Percent yield of Iron.
3e. What is the percent yield for a reaction when 6.50 grams of Fe2 O3 combines with carbon monoxide to produce 3.85 g of iron ? (not balanced) __Fe2O3 + __CO ---> __Fe + CO2
1.

15. 3f. Molecules of nitrogen dioxide.
3f. How many molecules of nitrogen monoxide is produced if 92.0 g of nitrogen dioxide is combine with excess water according to the following reaction? (Not balanced) __NO2(g) + __H2O(l) &#61614; __HNO3(g) + __NO(g)

2350 = 2.35 e + 03
1.

#### Solution Summary

The solutoin works on questions dealing with mole and Avogadro's Number.

\$2.19

1. Take a gas piston from the Glassware shelf and place it on the workbench. The gas piston is like a syringe, except that the piston/plunger is free to move up and down in order to equalize the pressure of its contents with the outside room pressure.

2. Take a balance from the Tools shelf and drop it on the gas piston. Record the mass of the empty gas piston.

3. Select a gas from the Chemicals shelf and fill the gas piston with 100 mL of the gas. Weigh the gas piston and gas and record the total mass.

4. Take four more gas pistons from the Glassware shelf and fill them each with 100 mL of one of the other four gases on the Chemicals shelf.

5. Weigh and record the total masses of each piston with gas.

6. Open the Data window and click on each gas piston. Record the molecular weight (MW) of each gas.

Questions

1. Record the mass of the empty gas piston (g):

2. For each gas, record the following:

(a) Name and formula
(b) Mass of gas piston and 100 mL gas (g)
(c) Mass of 100 mL gas (g)
(d) Molecular weight of the gas (g/mole)
(e) Number of moles in the 100 mL sample

% deviation = |(moles of gas) - (average for all gases)| / (average for all gases) * 100%

(a) Average number of moles in 100 mL for all five gases:
(b) % deviation for each gas: