1. Propylene oxide is used primarily in the synthesis of poly(propylene glycol),

Question

1. Propylene oxide is used primarily in the synthesis of poly(propylene glycol), a polymer material that is used in

the manufacture of automobile seats, bedding, and carpets. Propylene oxide is produced by the reaction of

tertiary-butyl hydroperoxide and propene. The compound tertiary-butanol is also produced.

a) Write the balanced chemical equation for the production of propylene oxide, using molecular formulas (You can use simple molecular instead of condensed structural. For example, the simple molecular formula for acetic acid is C2H4O2 and the condensed structural formula for acetic acid CH3COOH). Note that there are 2 reactants and 2 products.

b) What is the theoretical yield of propylene oxide (kg) if the reaction is performed using 110 kg each of both reactants?

c) If the percent yield was 82.5% on the reaction in (a), what was the actual yield of propylene oxide (kg) in this case?

2. Carbon dioxide gas reacts with solid lithium hydroxide to produce solid lithium carbonate and liquid water. The

carbon dioxide that an astronaut breathes out can be captured by passing it through a filter with the solid

lithium hydroxide.

a) Write a balanced chemical equation for the reaction.

b) If an astronaut typically exhales a total of 1.2 kg of carbon dioxide in one day, what mass of lithium

hydroxidecarbonate (kg) is required to completely react with this quantity of gas?

3. If ammonia gas is reacted with solid copper(II)oxide at elevated temperatures, the products are nitrogen gas and

solid pure copper and water vapour. In the lab, a student obtained 6.63 g of nitrogen gas when 18.1 g of

ammonia gas was reacted with 90.4 grams of copper(II)oxide. What was their percent yield? Make sure your

answer includes a balanced chemical equation for the reaction.

4. A student adds an excess (more than she needs to react completely) of solid sodium hydrogen carbonate to a

beaker containing exactly 675 mL of 0.220M coper(II)nitrate aqueous solution. A reaction occurs that produces

solid copper(II)carbonatesulfate, carbon dioxide gas, liquid water, and aqueous sodium nitrate.

a) Write a balanced chemical equation for the reaction.

b) Since the sodium hydrogen carbonate was added in excess, there will be some leftover. How much (g)?

c) What mass (g) of carbon dioxide gas will be produced?

5. In an experiment, you are instructed to make an aqueous solution that is 0.778 M potassium thiosulfate. You are

to use a 250.0-mL volumetric flask. What mass (g) of potassium thiosulfate do you need to weigh and add to the

flask to make this solution?

Explanation / Answer

1.

(a) Chemical eq.C4H10O2 + C3H6 = C3H6O + C4H10O

(b) 90 42 58 C4H10O2 will act as a limiting reagent.

90 g of C4H10O2 will react with 42 g of C3H6

so 110 kg of C4H10O2 will react with 42*110/90 (= 51.33 kg) of C3H6

90 g of C4H10O2 will produce 58 g of C3H6O

so 110 kg will produce 58*110/90(= 70.89 kg) of C3H6O

(c) 82.5/100 = x/70.89

x = 58.48 kg

2.

(a)Chemical eq. CO2 + 2LiOH = Li2CO3 + H2O

(b)44 g of CO2 react with 48 g of LiOH

so 1.2 kg will react with 48*1.2/44( = 1.31 kg) of LiOH

3.

3CuO + 2NH3 = N2 + 3Cu + 3H2O

90.4 18.1 6.63

238.5g of CuO will react with 34 g of NH3.

so 90.4 g will react with 34*238.5/90.4(=12.89 g )of NH3.

so CuO will act as a limiting reagent

238.5g of CuO will form 28 g of N2.

90.4g of CuO will form 28*90.4/238.5 ( = 10.6 g ) g of N2.

yield % = 6.63*100/10.6 = 62.5%

4.

2 NaHCO3 + Cu(NO3)2 = CuCO3 +CO2 + H20 + 2 NaNO3

mol wt. of Cu(NO3)2 = 249.5g

1000 * n /675 = 0.22

n= 0.1485 moles

weight of Cu(NO3)2 in solution = 0.1485 * 249.5 = 37.05g

249.5 g of Cu(NO3)2 produce 44g of CO2

so 37.05 g will produce 44*37.05/249.5= 6.534 g of CO2.

5. mol wt. of K2S2O3 = 190.32 g

1000 * n/ 250 = 0.778

n = 0.1945 moles

x /190.32 = 0.1945

x = 37.02 g

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