The temperature rises from 25.00°c to 29.00°c in a bomb calorimeter when 3.50 g of sucrose undergoes combustion in a bomb calorimeter. Calculate δerxn for the combustion of sucrose in kj/mol sucrose. The heat capacity of the calorimeter is 4.90 kj/°c. The molar mass of sugar is 342.3 g/mol.

Energy change for the combustion reaction = -1921.6 kJ/mol

Explanation:

Step 1: Data given

Initial temperature of calorimeter T1 = 25°C

Final temperature T2 = 29°C

Heat capacity of calorimeter c = 4.90 kJ/°C

Mass of sucrose  = 3.5 g

Molar mass of sucrose = 342.3 g/mol

Step 2: Calculate the heat gained

The change in temperature of calorimeter = T2 -T1 = 29.0 °C- 25.0 °C = 4.0°C

Heat gained by the calorimeter when the temperature changes by 4°C

= 4°C * 4.90 kJ/ 1 C = 19. 6 kJ

Step 3: Calculate moles of sucrose

moles sucrose = mass sucrose / molar mass sucrose

Moles sucrose = 3.50 grams / 342.3 g/mol

Moles sucrose = 0.0102 moles

Step 4: Calculate energy change for the combustion reaction

Energy change for the combustion reaction = -19.6 kJ/0.0102 moles  = -1921.6 kJ/mol

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.