Calculate the heat change associated

with cooling a 350.0 g aluminum bar

from 70.0/C to 25.0/C. Is the change

endothermic or exothermic? Why?

(-14.2 kJ)

Heat change is - 14,175 joules, Exothermic

Explanation:

We are given;

Mass of aluminium bar as 350.0 g initial temperature as 70.0 °C Final temperature as 25 °C

We are required to determine the heat change and indicate whether endothermic or exothermic;

We know that;

Heat change = Mass of a substance * specific heat * change in temperature

In this case;

Mass of Aluminium = 350.0 g

Change in temperature = (25 - 70)

= - 45° C

Specific heat of aluminium = 0.90 J/g°C

Therefore;

Heat change = 350.0 g * 0.90 J/g°C * - 45°C

=-14,175 joules

The heat change is exothermic because it is a negative value, also because cooling process involves heat loss and thus an exothermic reaction.