Question

I1. The pressure of a gas is given by Pwhere P is in atmosphere and V is in litres. If the gas expands from 20 to 60 L and undergocs an increase in internal energy of 225 cal. How much hcat will be absorbed during the process? 12. 5 moles of an ideal gas was initially at 315 K and 20 atm. The expansion of gas takes place adiabatically when the external pressure is reduced to 7 atm. What will be the final temperature and volume? Also calculate the work done during the process, given that Cp -8.58 cal/mol/ C.

can u show the 11th and 12th questions

Answer 1

11) Given V₁=20 L V​​₂=60 L

P=(15/V) where P is in atm and V is in Liter.

Internal Energy,

From 1st law of thermodynamics:

......(1)

Where

using equation (1) to fi​nd absorbed heat during this process as:

q= (941.850 - 16.48) J= 925.37J

12) No. of moles= 5 , initial temperature and pressure are

T₁= 315 K and P₁= 20 atm

Using Ideal gas law:

PV=nRT so, V₁= (nRT₁​/P₁) = (5×8.314×315) /(20×101325) = 6.46×10^-3 m³= 6.46 L

Since, the system is adiabatic so, it gives relation such as:

  

.... .(1)

Where P₂= 7 atm

Putting all the values in equation (1) to find final temperature as:

Simarly we will find final volume as:

And work done during this process is:

W=P_ext(V₂ - V₁) = (7×101325) ×(14.48 - 6.46) ×10^-3= 5688.4J=5.69KJ