Question

In 100 mL of 6.02 M HCl, which has a gravity of 1.10 g/ml, a strip of magnesium metal with a mass of 1.22 g dissolves. The initial temperature of the hydrochloric acid is 23.0 °C, and the end temperature of the solution is 45.5 °C. Calculate AH for the reaction under the conditions of the experiment. (The heat capacity of the calorimeter is 562 J/°C, specific heat of the finals is 4.184 /gºC.)
Mg(s) + HCl(aq) → MgCl2(aq) + H2(g)

Answer 1

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
All of the 1.22 g Mg metal will dissolve.
mass solution = 100 mL x 1.10 g/mL = 110 g
q total = qrxn + Ccal*delta T
qtotal = (mass solution x specific heat solution x delta T) + Ccal*delta T
q = (110 g x 4.184 J/g*c x (45.5 - 23.0) + [562 J/c x (45.5-23.0)]
That is q for 1.22 g Mg.
Then convert to kJ/mol and you have it.