Question

7. Foam cup A has 36 mL of water that contain 2 moles of HCL at 20°C. Foam cup B has 36 mL of water that contain 2 moles NaOH of at 20°C. The contents of foam cup A are added to foam cup B and a chemical reaction occurs. The final temperature of the contents of cup B is 31°C. Calculate the enthalpy change of the reaction. The density of each solution is 1g/ml.A.-1.66 kj B.-3.31 kj C.-6.62 kj D.-13.2

Answer 1

i just took the quiz the correct answer is actually B.-3.31 kj

Answer 2

Answer:The correct answer is option B.

Explanation:

Cup A - 36 ml of the 2 moles of HCl.

Density of the solution = 1 g/ml

Mass of the solutionm,M:$density \times volume=1 g/ml\times 36 ml=36 g$

Cup B - 36 ml of the 2 moles of NaOH

Density of the solution = 1 g/ml

Mass of the solution ,M': $density \times volume=1 g/ml\times 36 ml=36 g$

On mixing both the solution, heat of neutralization was released which can be termed as enthalpy change of the reaction:

Mass of the solution after mixing,m = M+M'=36 g+ 36 g = 72 g

Change in temperature of the solution.$\Delta T=31^oC-20^oC=11^oC$

Specific heat capacity of water , c= 4.186 J/g °C

$Q=mc\Delta T$

$Q=72 g\times 4.186 J/g^oC\times 11^oC=3315.312 J=3.315 kJ$

The energy absorbed by the water from the reaction between both solution is 3.315 kJ which means that energy was released during the reaction between the HCl and NaOH that is -3.31 kJ. Negative sign indicates that energy is released during the reaction.

Hence, the correct answer is option B.