Answer to Question #144850 in General Chemistry for carl

Question

Freon-12 is used as a refrigerant in central home air conditioners. The rate of effusion of Freon-12
to Freon‐11 (molar mass = 137.4g/mol) is 1.07:1. The formula of Freon‐12 is one of the following:
CF4, CF3Cl, CF2Cl2, CFCl3, or CCl4.
Which formula is correct for Freon-12?
Let Freon‐12 = gas 1 and Freon‐11 = gas 2:

Answer 1

$rate_e(Freon12)/rate_e(Freon11) =$

$= \sqrt {M(Freon11)/M(Freon12)} = 1.07/1$

$M(Freon12) = M(Freon11)/1.07^2 =$

$= 137.4g/mol /1.07^2 \approx 120g/mol$

M of all options available:

$M(CF_4) = 88g/mol$

$M(CF_3Cl) = 104.5 g/mol$

$M(CF_2Cl_2) = 121g/mol$

$M(CFCl_3) = 137.4g/mol$

$M(CCl_4) = 154g/mol$

The closest to the computed value is $CF_2Cl_2$

Answer:

Freon-12 is $CF_2Cl_2$