water in an electric kettle is brought to boil in 180s by raising its temperature from 20°c to 100°c. it then takes a further 1200s to boil the kettle dry. calculate the specific latent heat of vaporisation of water, l,at 100°c. the specific heat capacity of water is 4200j/kg/k.
state any assumptions made.

2-24×10^6J/kg

Explanation:

first calculate amount of heat required to raise temperature of water from 20 deree C 100 Degree C. divide this by time 180 to get power of kettle . assume there is 1 kg of water. using power of kettle calculate heat energy required to vapourise water by multiplying it by 1200. now calculate Lv by using formula

Lv = heat given / mass vapourised

see attachment