Question

What will be change in internal energy of oxygen when 1 mole of it is heated from
10°C to 20°C at constant volume? Given Cp=8cal mol ''C​

Answer 1

Solution :-

Change in internal energy of the gas ,

$\rm \: ∆U = nC_v∆T$

where, n is the number of moles of gas, $\rm{C_v}$ is molar heat capacity at constant volume and ∆T is change in temperature.

We know that, $\rm \: C_p - C_v = R$

$\: \: \: \: \: \: \: \therefore \: \rm \: C_v = C_p - R$

Given that, $\rm C_p$ =8 cal/mol. °C and

R = 8.36 J/mol. °C or 2 J/mol. °C

So, $\rm \: C_v \: =$ 8 - 2 = 6 cal/mol. °C

Now,

Change in internal energy of the gas,

⟶ 5 × 6 × ( 20 - 10 )

⟶ 30 × 10

⟶ 300 J

Hence, 300J is the answer of this question.