Question

Question #1bbbc

Answer 1

You will require a sample of impure `CaC_2` that is 10.02 g in mass.

Explanation:

The equation for acetylene production is

`CaC_2 + 2H_2O rarr C_2H_2 + Ca(OH)_2`

At STP, 3.36 L of any gas represents `3.36-:22.4 = 0.15 mol`

Since the ratio between `CaC_2` and `C_2H_2` is 1 to 1 in the equation, we require 0.15 mol of calcium carbide to do the job.

The molar mass of `CaC_2` is 64.1 g, so 0.15 mol would have a mass of 9.615 g.

Since the sample is 4% impure, the 9.615 g must represent 96% of the mass of the impure sample, so the sample must be

`9.615 -: 0.96 = 10.02 g` in size.