Question

What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g/mL by 3.33 °C? (The specific heat of the solution is 3.74 joules/gram-K.) What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g/mL by 3.33 °C? (The specific heat of the solution is 3.74 joules/gram-K.) -3.89 -7.43 8.20 6.51 -12.51

Answer 1

Answer:

-3,89

Explanation:

First to consider is that the reaction is raising the temperature of the solution, so it's an exothermic reaction.

The enthalpy can be calculated by the following equation:

$H=m*C_{p} *ΔT$

First we need to calculate the mass using the density and the volume:

$d=\frac{m}{V}$ ⇒ $m=d*V$

$m=250[mL]*1,25[\frac{g}{mL}]=312,5 [g]$

Then we have Cp = 3,74 Joules/gram°K  ΔT = -3,33 °C (cause of exothermic reaction)

Replacing in the formula:

$H=312,5*3,74*(-3,33)=-3891 [J]=-3,81[kJ]$