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Question: What amount of heat must be supplied to 35 g of oxygen at room temperature to raise its temperature ...

What amount of heat must be supplied to 35 g of oxygen at room temperature to raise its temperature by 80°C at constant volume (molecular mass of oxygen is 32 and

R = 8.3 J mol–1 k–1)

A

1.52 kJ

B

3.23 kJ

C

1.81 kJ

D

1.62 Kj

Answer

1.81 kJ

Explanation

Solution

: here mass of oxygen (m) = 35g

Molar mass of O2(M)=32 g mol−1\mathrm { O } _ { 2 } ( \mathrm { M } ) = 32 \mathrm {~g} \mathrm {~mol} ^ { - 1 }

Rise in temperature, ΔT=80∘C\Delta T = 80 ^ { \circ } \mathrm { C }

n=mM=3532=1.09 moln = \frac { m } { M } = \frac { 35 } { 32 } = 1.09 \mathrm {~mol}

As oxygen is diatomic gas, then molar specific heat at constant volume is CV=52RC _ { V } = \frac { 5 } { 2 } R

And amount of heat supplied to gas

ΔQ=nCVΔT\Delta Q = n C _ { V } \Delta T

=1.09×52R×80=1.09×52×8.3×80= 1.09 \times \frac { 5 } { 2 } R \times 80 = 1.09 \times \frac { 5 } { 2 } \times 8.3 \times 80 =1809.4J=1.8094KJ≈1.81Kj= 1809.4 J = 1.8094 K J \approx 1.81 \mathrm { Kj }