Question

amount of heat required for 200 g water to heat from 20°c to 40°c

Answer 1

Amount of heat ΔQ = m.c.Δθ Note:m = mass of water = 200g = 0.2 kgc = specific heat capacity of water, C = 4000J/KgºCΔθ = change in temperature
ΔQ= 0.2x4000(40−20)     = 16,000J     = 16kJ

Answer 2

Given:
Mass =m= 200g
Specific heat of water= 1 cal / g °c
Temperature difference=ΔT = 40-20=20°c
Heat = Q=?
formula to be used:

Q= msΔT
=200x1x20= 4000 calories

1cal=4.18 joules
Q= 4000x4.18
= 16,720 joules
Amount of Heat required is 4000 calories or 16,720 joules