Verified answer

Nothing to do with delta t, darling. The heat energy required is the same regardless of how long it takes.

As the previous respondent said, you multiply the change in temperature, the mass (in grammes, lets say) and the energy required to increase the temperature of one gramme of water by one degree. Simple, really. That quantity, the specific heat capacity of water, is about 4 Joules per gramme per degree Celsius.

350*4.184*(65-15)

Now, 350g is how much water you have.

4.184/1gdegreeC is your specific heat of water.

65-15 = temperature change degree C.

Multiply that together to get heat. :)

Hope this helps!