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1. For the reaction represented by the equation 2Na + 2H2O → 2NaOH + H2, how many grams of sodium hydroxide are produced from 3.0 mol of sodium with an excess of water?

a. 40g

b. 80g

c. 120g

d. 240g

2. A chemist interested in the efficiency of a chemical reaction would calculate the

a. mole ratio

b. energy released

c. percent yield

d. rate of reaction

3. For the reaction represented by the equation: CH4+ 2O2→ 2H2O + CO2 calculate the percentage yield of carbon dioxide if 1000. g of methane react with excess oxygen to produce 2300. g of carbon dioxide.

a. 83.88%

b. 89.14%

c. 92.76%

d. 96.78%

4. If 1 egg and 1/3 cup of oil are needed for each bag of brownie mix, how many bags of brownie mix do you need if you want to use up 3 eggs and 1 cup of oil?

a. 1

b. 2

c. 3

d. 4

5. In the reaction, 2CO + O2 -> 2CO2, what is the ratio of the moles of O2 used to moles of CO2 produced?

a. 1:1

b. 2:1

c. 1:2

d. 2:2

6. How many moles of aluminum are needed to react completely with 1.2 mol of FeO?

2Al(s) + 3FeO(s) → 3Fe(s) + Al2 O3 (s)

a. 1.2

b. 1.6

c. 2.4

d. 0.8

7. How many liters of NH3 are needed to react completely with 30.0 L of NO (at STP)?

4NH3 + 6NO--- > 5N2 + 6H2O

a. 20L

b. 7.5L

c. 120L

d. 5L

8. How many liters of NH3 , at STP, will react with 5.3 g O2 to form NO2 and water?

4NH3 + 7O2--- > 4NO2 + 6H2O

a. 0.00423L

b. 2.12L

c. 3.03 L

d. 6.49 L

9. How many grams is 7 mol of K2SO4?

a. 120grams

b. 110grams

c. 3.5 kg

d. 1.2kg

10. If you have 7.22 x 1024 atoms of Ni, how many moles of Ni do you have?

a. 12 mol

b. 9 mol

c. 0.5 mol

d. 4.2 mol

1 Answer

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Best answer

1-?

2-C

percentage yield shows how much actual yield over theoretical yield so is good for efficiency

3-?

4-C

1x3=[3] (1/3)x[3]=1 therefore answer is 3

5-C

x1 O2 : x2 CO2 = 1:2

6-D

1.2 divided by the molar ratio 1.2x(2/3) = 0.8

7-A

30 divided by molar ratio 30 x(4/6)=20

8-?

9-D

Mass = Moles x Molar Mass (7 x (39+39+32+16+16+16+16))= roughly 1200g

10-A (assuming 1024 =10^24)

Moles = Number of Atoms / Avodagro's Constant = 7.22x10^24 / 6.0221417930×10^23 = Roughly 12

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