How to Calculate Heat Produced by a Coffee Cup Calorimeter Reaction?

[Bcranger 0]

Homework Statement

The reaction of 0.050 g of solid Mg with 100.0 mL of 1.00M aqueous HCl solution is carried out in a coffe-cup calorimeter. The temperature of the solution increases from 22.21 degrees Celsius to 24.46 degrees Celsius. How much heat is produced by the reaction?

Homework Equations

Q = m*c*Δt

Mg + 2HCl → MgCl2 + H2

The Attempt at a Solution

mols Mg = .002057
mols HCl = .1
Limiting Reactant = Mg
Δt = 2.25 degrees Celsius

I am confused since there is no water involved in the reaction. Assumptions I was given are:
1. The specific heat/molar heat of a calorimeter is small and can be ignored.
2. The specific heat/molar heat of a dilute aqueous solution is the same as that of water, c = 4.184 J/g°C.
3. The densities of dilute aqueous solutions are approximately 1.00 g/mL.

I believe I am to use the Q = mct equation. I know the specific heat, c, should be 4.184, and that the change in temperature is 2.25 degrees Celsius. However, I am not sure what to put for m, the mass. Should m be the total mass of everything or just the mass of the substances actually used in the reaction that takes place?

 

[Nino MMP]

If m is the mass of the substances used in the reaction, then m = 0.050 g Mg + (100 mL)(1.00 g/mL) = 100.5 g. Q = (100.5 g)(4.184 J/g °C)(2.25 °C) = 883.945 J. Is this the correct approach?