When a solid dissolves in water, heat may be evolved or absorbed. the heat of dissolution (dissolving) can be determined using a coffee cup calorimeter. in the laboratory a general chemistry student finds that when 24.22 g of babr2(s) are dissolved in 118.20 g of water, the temperature of the solution increases from 24.85 to 28.18 °c. the heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be 1.84 j/°c. based on the student's observation, calculate the enthalpy of dissolution of babr2(s) in kj/mol. assume the specific heat of the solution is equal to the specific heat of water.

The enthalpy of dissolution of BaBr2 (s) is - 8,94 kJ/mol

Explanation:

In a dissolution process, the heat is released, so it must be negative (-)

The same to ΔH.

Q = m . C . ΔT

Q = 118,2 g . 1,84 J/g°C . (Tfinal - Tinitial)

Q = 118,2 g . 1,84 J/g°C . (28,18°C - 24,85°C)

Q = 118,2 g . 1,84 J/g°C . 3,33°C

Q = 724,2 J

724,2 J / 1000 = 0,7242 kJ

We dissolved 24,22g of BaBr2

Molar mass BaBr2: 297,13 g/m

We dissolved 24,22 g/ 297,13 g/m = 0,081 moles

ΔH = kJ/mol

ΔH = -0,7242 kJ/ 0,081 mol

ΔH = -8,94kJ/mol

the answer

explanation:

the capillary tube was too close to the bottom of the beaker.

the ruler may have moved.

water got into the capillary tube.

the temperature was not allowed to equilibrate in the 2-4 minutes.