7. How many liters of NH3, at STP will react with 10.6 g O2 to form NO2 and water? 4NH3 (g) + 7O2 (g) → 4NO2 (g) + 6H2O (g) *

a. 2.12 L

b. 3.03 L

c. 4.24 L

d. 6.49 L

8. What is the maximum number of grams PH3 that can be formed when 3.4 g of phosphorus reacts with 4 grams of hydrogen to form PH3? P4 (g) + 6H2 (g) → 4PH3 (g) *

a. 3.7 g

b. 6.8 g

c. 45 g

d. 270 g

9. Which of the following is NOT true about percent yield? *

a. Percent yield is often less than 100%

b. Percent yield measures the efficiency of a reaction carried out in a lab.

c. Percent yield of 100% is unlikely when reactants or products were not carefully measured.

d. Percent yield is the ratio of theoretical yield to actual yield expressed as a percent.

Question

Luz Choi

Chemistry

12 December, 20:05

7. How many liters of NH3, at STP will react with 10.6 g O2 to form NO2 and water? 4NH3 (g) + 7O2 (g) → 4NO2 (g) + 6H2O (g) *

a. 2.12 L

b. 3.03 L

c. 4.24 L

d. 6.49 L

8. What is the maximum number of grams PH3 that can be formed when 3.4 g of phosphorus reacts with 4 grams of hydrogen to form PH3? P4 (g) + 6H2 (g) → 4PH3 (g) *

a. 3.7 g

b. 6.8 g

c. 45 g

d. 270 g

9. Which of the following is NOT true about percent yield? *

a. Percent yield is often less than 100%

b. Percent yield measures the efficiency of a reaction carried out in a lab.

c. Percent yield of 100% is unlikely when reactants or products were not carefully measured.

d. Percent yield is the ratio of theoretical yield to actual yield expressed as a percent.

+2

Answers (1)

Know the Answer?

Bria Chan · Answer 1

7)

Moles of oxygen = 0.33

Moles of ammonia required = 0.189

Volume of one mole of gas at STP = 22.4 L

Volume ammonia = 22.4 x 0.189

Volume of ammonia = 4.23 L

The answer is C.

8) Moles of phosphorus = mass / Ar

Moles phosphorus = 3.4 / (31 x 4)

Moles phosphorus = 0.027

Mass of hydrogen required = 0.027 x 6 x 2

Mass of hydrogen required = 0.324

So phosphorus is limiting

Moles of PH3 formed = 3 x 0.027

Moles of PH3 formed = 0.108

Mass of PH3 formed = 0.108 x (31 + 4)

Mass of PH3 = 3.78 grams

9) D

The percentage yield is the ratio of actual yield to the theoretical yield expressed as a percent.