Answer:
4,10kJ
Explanation:
The reaction of phosphoric acid (H₃PO₄; MW: 97.994 g/mol ) with sodium hydroxide (NaOH; MW: 40 g/mol) is:
H₃PO₄ + NaOH ⇄ H₂PO₄⁻ + Na⁺ + OH⁻
Now, the energy produced for the change in temperature in a calorimeter is:
Q = -H×m×ΔT - C×ΔT
Where H×m×ΔT is the energy absorbed for the system and C×ΔT is the energy absorbed for the calorimeter.
Replacing:
Q = -4.00J/g°C × 103,5g × (31,5°C-22,3°C) - 31,72J/°C × (31,5°C-22,3°C)
H is heat capacity of the system, ΔT is change in temperature, m is total mass of the system: 52,0g + 51,5g = 103,5g and C is calorimeter constant.
Q = -4100J ≡ -4,10kJ
I hope it helps!
