The amount of heat that must be supplied to 35 g of oxgen at room temperature to raise its temperature by `80^(@) C` at constant volume is
(Molecular mass of oxygen is 32 and `R = 8.3 J mol^(-1) K^(-1)` )

Options

A. 2.84 kJ
B. 1.68 kJ
C. 1.81 kJ
D. 2.88 kJ

Answer

C

Explanation

Given, weight of oxygen = 35g, molecular weight of oxygen = 32, change in temperature dT ` =80^(@)` C and R = `8 . 3J mol^(-1) K^(-1)`
Heat supplied at constant volume, Q ` = nC_(v) dT`
`:. n = ("weight of oxygen")/("gram molecular weight of oxygen") = (35)/(32)`
`:.O_(2)` is diatomic gas therefore, the specific heat capacity at constant volume,
`C_(v) = (5)/(2)R`
`:. Q = ((35)/(32))((5)/(2)R) (80) = ((35)/(32)) ((5)/(2)) xx 8.3 xx 80`
`rArr q = 1815.625 J or Q = 1.81 KJ`