Question

An open flask contains air at ${27}^{o}C$. To what temperature it must be heated to expel one-fourth of the air?

Answer 1

Initial temperature = 300 K

Let no. of a mole at 300K = n

Let new temperature be = T K

mole coming out at T K = $\frac{1}{4}$ n

mole left at T K $=n-$ $\frac{1}{4}$

=$\frac{2}{3}$ n

under constant p and v: $n_1{T}_1=n_2{T}_2$

$n\times 300=$ $\frac{2}{3}$$n\times T$

$T=450K$