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 ÄErxn 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.

- 1.92 x 10^3 kJ/mole

1960 j

To calculate the ΔErxn (change in energy) for the combustion of sucrose in kJ/mol sucrose, you need to use the heat capacity of the calorimeter and the temperature change during the reaction.

First, convert the mass of sucrose to moles using the molar mass of sucrose:
Molar mass of sucrose = 342.3 g/mol
Mass of sucrose = 3.50 g
Number of moles of sucrose = Mass of sucrose / Molar mass of sucrose

Next, calculate the heat released or absorbed during the reaction using the formula:
ΔErxn = Ccal × ΔT
where ΔErxn is the change in energy, Ccal is the heat capacity of the calorimeter, and ΔT is the temperature change.

Given:
Ccal = 4.90 kJ/°C
ΔT = final temperature - initial temperature

Now you have all the values to calculate ΔErxn:
ΔErxn = Ccal × ΔT

Substitute the given values and calculate the change in energy.

Finally, to get the ΔErxn per mole of sucrose, divide the ΔErxn by the number of moles of sucrose calculated earlier. This will give you the ΔErxn in kJ/mol sucrose.

q = [mass H2O x specific heat H2O x (Tfinal-Tinitial)] + [Ccal x 4.90]

That gives q for 3.50g sucrose.
(q/3.5) x (mol mass sucrose/1 mol) = q/mol = delta Erxn