Answer to Question #111051 in Chemistry for emily

Question

How much heat is lost when a 56g glass of 80 °C water cools down to 0 °C.

Answer 1

Solution:

To calculate the amount of heat entering or leaving a system, the equation Q = mcΔT is used.

m = mass (in grams)

c = specific heat capacity (J/g°C)

ΔT = change in temperature (°C).

Specific heat of water is 4.18 J/g^oC

ΔT = (T_final - T_initial) = 0°C - 80°C = -80°C

Then,

Q = mcΔT = (56 g) * (4.18 J/g°C) * (-80°C) = -18726.4 J = -18.73 kJ.

Q = -18.73 kJ.

The negative Joule value means heat is being lost in an exothermic reaction.

Answer: Q = -18.73 kJ.