Types: A
`Q= mcDelta` (Heat energy during change in temperature)
Q = mL (Heat energy during change of state )
Note : Specific heat capacity (c) ` =1 cal // g^(@)C = 1` `kcal // kg^(@) C`
`Delta T` = Higher temperature - Lower temperature .
How much heat energy is necessary to raise the temperature of 5kg of water form `20^(@)` C to `100^(@)`C.

Explanation

Mass (m) =5 kh
Temp. difference `(Delta T)= 100-20 = 80^(@)C`
Speific heat capacity (c) = ` 1 kcal//kg^(@)C`
To find : Heat energy (Q) = ?
Formula : Q = mc`DeltaT`
Solution ` : Q = 5xx 1xx 80`
` = 400 kcal`
Heat energy needed is 400 kcal.