Question

In a constant‑pressure calorimeter, 70.0 mL of 0.350 M Ba(OH)2 was added to 70.0 mL of 0.700 M HCl. The reaction caused the temperature of the solution to rise from 23.97 ∘C to 28.74 ∘C. If the solution has the same density and specific heat as water, what is heat absorbed by the solution? Assume that the total volume is the sum of the individual volumes. (And notice that the answer is in kJ).

Answer 1

Answer: The amount of heat absorbed by the solution is 2.795 kJ

Explanation:

To calculate the mass of water, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of water = 1 g/mL

Volume of water = [70 + 70] = 140 mL

Putting values in above equation, we get:

$1g/mL=\frac{\text{Mass of water}}{140mL}\\\\\text{Mass of water}=(1g/mL\times 140mL)=140g$

To calculate the heat absorbed, we use the equation:

$q=mc\Delta T$

where,

q = heat absorbed

m = mass of water = 140 g

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

$\Delta T$ = change in temperature = $T_2-T_1=(28.74-23.97)^oC=4.77^oC$

Putting values in above equation, we get:

$q=140g\times 4.186J/g^oC\times 4.77^oC=2795.4J=2.795kJ$

Hence, the amount of heat absorbed by the solution is 2.795 kJ