2. Cryofluorane, also known as Freon 114, is a chlorofluorocarbon which was once

Question

2. Cryofluorane, also known as Freon 114, is a chlorofluorocarbon which was once used as a refrigerant and an aerosol propellant. It contains carbon, fluorine, and chlorine. The percent composition of this substance is 14.05%C, 44.46%F, and 41.48%Cl. What is the empirical formula of cryofluorane? (Write the symbols in the order C, F, Cl.)

3. The lunar module (LM) which was used to land on the surface of the moon during the Apollo missions used a mixture of hydrazine, N2H4, and dinitrogen tetroxide, N2O4, as a fuel source (the molar masses of the reactants and products are written under the equation):

2N2H4(l) + N2O4(l) 3N2(g) + 4H2O(g)

32.05 g/mol 92.01 g/mol 28.01 g/mol 18.02 g/mol

During an experiment, 325 g of N2H4 and 325 g of N2O4 are mixed.

a. Which of the two reactants is the limiting reagent, and what is the theoretical yield of N2?

b. How many grams of excess reagent will be left over?

4. Acrylonitrile (C3H3N) is the starting material for many synthetic carpets and fabrics. It is produced by the following reaction:

2C3H6(g) + 2NH3(g) + 3O2(g) 2C3H3N(g) + 6H2O(g)

If 5.00 g C3H6, 20.0 g O2, and 15.0 g NH3 are reacted, what is the limiting reactant, and what is the theoretical yield of acrylonitrile?

5. A solution made by dissolving 4.875 g of sodium sulfate with water to make 200.0 mL of solution. Calculate the molarity of the solution.

6. How many grams of magnesium chloride are in 225 mL of a solution that has a concentration of 0.55 M?

Explanation / Answer

Ans 3

2N2H4(l) + N2O4(l) 3N2(g) + 4H2O(g)

Part a

From the stoichiometry of the

2 mol of N2H4 reacts with = 1 mol of N2O4

(2*32.05 =) 64.10 g N2H4 reacts with = 92.01 of N2O4

325 g N2H4 reacts with = 92.01 x 325/64.10 = 466.51 g of N2O4

But we have only 325 g of N2O4

Limiting reactant = N2O4

Excess reactant = N2H4

Theoretical yield of N2 = 3*28 g N2 x 325 g N2O4 / 92.01 N2O4

= 296.71 g

Part b

Excess reactant remains( N2H4) = initial - consumed

= 325 - (64.10 x 325/92.01)

= 325 - 226.42

= 98.58 g

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