A0.5865-g sample of lactic acid (hc3h5o3) is burned in a calorimeter whose heat capacity is 4.812 kj/oc. the temperature increases from 23.10 °c to 24.95 °c. calculate the heat of combustion of lactic acid (a) per gram and (b) per mole.

a) 15.2 kJ/g

b) 1367 kJ/mol

Explanation:

Given:

Mass of lactic acid = 0.5865 g

Heat capacity C of calorimeter = 4.812 kJ/C

Initial temperature, T1 = 23.10 C

Final temperature, T2 = 24.95 C

To determine:

Heat of combustion/gram and heat/mole lactic acid

Calculation:

Molar mass of lactic acid = 90.08 g/mol

The heat of combustion is given as:

where C = heat capacity of calorimeter

T1 and T2 are the initial and final temperatures

a) heat of combustion per gram

b) heat of combustion per mole

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.