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

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:

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

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

Finally, the enthalpy of reaction is:

And in kJ:

Best regards!

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

it is the most commonly accepted one