First Law

Question 1

first law of thermodynamics

Answer 1

increase in IE is the sum of work done on system and heat supplied to system

Question 2

why specific latent heat of vap. greater than specific latent heat of fus.?

Answer 2

• when evaporating, greater change in separation of atoms
• greater change in PE & IE
• greater change in volume, greater work done

Question 3

i) why external work is done on boiling water
ii) why there’s a change in U as water becomes steam

Answer 3

i) • vol increases on evaporation
• work done pushing back the atm
ii) • constant KE as temp constant
• increasing PE as separation of atoms increases
• U = KE + PE, hence U increase