Question

100 mL of a 0.300 M solution of AgNO3 reacts with 100 mL of a 0.300 M solution of HCl in a

coffee-cup calorimeter and the temperature rises from 21.80 °C to 23.20 °C. Assuming the density
and specific heat of the resulting solution is 1.00 g/mL and 4.18 J/g. °C, respectfully, what is the
AHºx?
A 39.0 kJ/mol
B +39.0 kJ/mol
C.+1.17 kJ/mol

Answer 1

`\Delta _rH=-39,1kJ`

Step-by-step explanation:

Hello!

In this case, since it is possible to assume that the heat released by the reaction is absorbed by the water in the calorimeter we can write:

`Q_(rxn)=-200mL*(1g)/(1mL)*4.184(J)/(g\°C)*(23.20\°C-21.80\°C)\\\\Q_(rxn)=-1,171.5J`

Now, since the reaction between silver nitrate and hydrochloric acid is:

`HCl+AgNO_3\rightarrow AgCl+HNO_3`

We can see there is a reacting 1:1 mole ratio, thus, the reacting moles are computed via the molarity of the solutions:

`n=0.300mol/L*0.100L=0.0300mol`

Finally, the enthalpy of reaction is:

`\Delta _rH=(-1,171.5J)/(0.0300mol)=-39,050.7J`

And in kJ:

`\Delta _rH=-39,1kJ`

Best regards!