A cylinder of fixed capacity 44.8 litres contains helium gas at standard temperature and pressure. What is the amount of heat needed to raise the temperature of the gas in the cylinder by 15.0^(@)C ? (R= 8.31Jmol^(-1)K^(-1))

A cylinder of fixed capacity 44.8 litres contains helium gas at standa

1.	A cylinder of fixed capacity 44.8 litres contains helium gas at standard temperature and pressure. What is the amount of heat needed to raise the temperature of the gas in the cylinder by 15.0^(@)C ? (R= 8.31Jmol^(-1)K^(-1))
Answer» Solution :We know that 1 mol of any (ideal) gas at STP occupies a VOLUME of 22.3 litres. Thus the cylinder in this example contains 2 mol of helium. SINCE helium is monatomic ,molar specific heat at constant volume ,`C_(v)=(3//2)R` , and molar specific heat at constant pressure ,`C_(P)=(5//2)R` `THEREFORE` The Heat required to raise the temperature by `15^(@)`C DQ= `ne_(V)dt=2xx1.5Rxx15.0=45R` `=45xx8.31`=374J (approximately)