Question

7. A 26.4-ml sample of ethylene gas, C2H4, has a pres-sure of 2.50 atm at 2.5°C. If the
volume is increased to 36.2 mL and the temperature is raised to 10°C, what is the
new pressure. (Hint: Three variables have been given so what equation will you
use?)

Answer 1

Answer: 1.87 atm

Explanation:

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is,

$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$

where,

$P_1$ = initial pressure of gas = 2.50 atm

$P_2$ = final pressure of gas = ?

$V_1$ = initial volume of gas = 26.4 ml

$V_2$ = final volume of gas = 36.2 ml

$T_1$ = initial temperature of gas = $2.5^oC=273+2.5=275.5K$

$T_2$ = final temperature of gas = $10^oC=273+10=283K$

Now put all the given values in the above equation, we get:

$\frac{2.50\times 26.4}{275.5}=\frac{P_2\times 36.2}{283}$

$P_2=1.87atm$

The new pressure is 1.87 atm by using combined gas law.