Question

10) Two solutions, initially at 24.69°C, are mixed in a coffee cup calorimeter. When a 100.0 mL volume of 0.100 M AgNO3 solution is mixed with a 200.0 mL sample of 0.100 M NaCl solution, the temperature in the calorimeter rises to 25.16°C. Determine the AHºrn, in units of kJ/mol. The limiting reactant for this problem AgNO3. Assume that the density and heat capacity of the solutions is the same as that of water. AH = = Clan M.41! Write a balanced reaction: AgNO₃ + Nach Ag Cl + NaNO3 Determine the heat for reaction (the system): Determine the AHⓇrxn, in units of kJ/mol.

Answer 1

The balanced chemical reaction is

        AgNO3(aq) + NaCl(aq) ------> AgCl(s) + NaNO3(aq)

Number of mmoles of AgNO3 = 100*0.100 = 10 mmoles

Total volume of the solution = 100+200 = 300 mL

Mass of the mixture = v*d = 300*1 = 300 gms

Heat evolved in the reaction (q) = msDT                                                       
                                                                                                    
                = 300 × 4.184*(25.16 – 24.69) = 589.944 j
              
                = 0.589 kJ

Number of moles of AgNO3 = 100*0.100/1000 = 0.01 moles
                         
0.01 moles of 0.1 M AgNO3 liberates 0.589 kJ

1 mole 0f 0.1 M AgNO3 liberates

i.e. (-0.589)/0.01

      = -58.9 kJ

$\Delta$ Hrxn = -58.9 KJ/mole