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The high heat capacity of water is ecologically benign because it stabilizes the

ID: 945939 • Letter: T

Question

The high heat capacity of water is ecologically benign because it stabilizes the temperatures of lakes and oceans: a large quantity of energy must be lost or gained before there is a significant change in temperature. Conversely, it means that a lot of heat must be supplied to achieve a large rise in temperature. The molar heat capacity of water is 75.3 J K1 mol1 . What energy is needed to increase the temperature of 250g of water (a cup of coffee, for instance) by 40 degrees Celcius.

Show work in detail, and list equations used

40 degrees C is 313.15K

Explanation / Answer

q = mC(T2 - T1)

q = heat energy needed = ?

m = mass of water = 250 g = 0.25 kg

C = molar heat capacity of water = 75.3 JK-1mol-1

(T2-T1) = Change in temperature = 313.15 K

q = 0.25 * 75.3 (313.15) = 5895 J