some thermochemistry

[Dorkhedeos]

how many joules(or calories) of heat are required to heat water from 60 degrees F to 75 degrees F?


Edit: whoops, forgot the amount. its 11,356g

 

[Opcn]

Well, a callorie is the amount of energy needed to heat 1 ml (also 1 gram) of water 1 degree celcius, so 15 degrees F /72 times 40 is equal to 8.333 so 8.3333deg C X 11,356g=94633.333333 calories or 94.633 Callories or to get Joules multiply by 4.1868 to get 396210.84, Not to sure abput significant figures,

 

[Bignose]

Opcn's calcualtions are spot on. There is a small error in assuming a constant heat capacity of water, since heat capacity is weak function of temperature. From the CRC handbook of chemistry and physics

Temp (deg C) / Heat Capacity J/g*K
0 / 4.2176
10 / 4.1921
20 / 4.1818
30 / 4.1784
40 / 4.1785
50 / 4.1806
60 / 4.1843
70 / 4.1895
80 / 4.1963
90 / 4.2050
100 / 4.2159

But none of these numbers is more than like 0.1% different than the 4.1868 number Opcn used. I know there is a polynomial fit for the heat capacity in Smith, Van Ness and Abbott. It is in the form Cp = a + bT + cT^2 + dT^-2. There would also be a pressure dependence, but again that should be exceptionally weak. For practially all applications, opcn's calcs are more than good enough.

p.s. No chemistry in this question, this was thermodyanmics or really thermostatics, so your title ain't quite right. Though if it was meant to get opcn's and my attention is was good advertising!