Question

When 10.g of CH3COOH is combusted in a sealed calorimeter, it releases enough energy to heat 2000. g of water from 23.5 °C to 34.3 °C. a. Calculate the energy released per 10 g of CH3COOH. b. Calculate the energy released per mole of CH3COOH.

Answer 1

a. 90.288 kJ.

b. - 54.06 kJ/mol.

Step-by-step explanation:

a. Calculate the energy released per 10 g of CH₃COOH.

• We can calculate the amount of heat (Q) released to water using the relation:

Q = m.c.ΔT,

where, Q is the amount of heat released to water (Q = ??? J).

m is the mass of water (m = 2000.0 g).

c is the specific heat capacity of solution (c = 4.18 J/g.°C).

ΔT is the difference in T (ΔT = final temperature - initial temperature = 34.3°C - 23.5°C = 10.8°C).

∴ Q = m.c.ΔT = (2000.0 g)(4.18 J/g.°C)(10.8°C) = 90288 J = 90.288 kJ.

b. Calculate the energy released per mole of CH₃COOH.

• To find ΔH:

∵ ΔH = Q/n

no. of moles of CH₃COOH (n) = mass/atomic mass = (10.0 g)/((60.052 g/mol) = 0.167 mol.

∴ ΔH = - Q/n = - (90.288 kJ)/(0.167 mol) = - 54.06 kJ/mol.

The negative sign is not from calculation, but it is an indication that the reaction is exothermic.