Enthelpy change of reaction with calorimeter

[nicolodn]

Homework Statement

Student uses another calorimeter with a heat capacity of 133.2 J/°C. S/he fills the calorimeter with 100.0 g of 25.00°C dilute HCl solution and adds 0.496 g Mg metal (24.3 g/mol). The final temperature of the apparatus comes to 41.37°C.
What is the enthalpy change for the reaction as written?

Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)

Take the specific heat capacity of the dilute acid solution as being equal to that of water, and neglect the heat capacity of the magnesium metal.

Hint: the heat evolved by the Mg reaction is gained by the water and calorimeter

Homework Equations

The Attempt at a Solution

m x C x T + c x T

 

[jbsteele]

= m x C x T 100 g HCl x 4.18 J/g°C x (41.37°C - 25°C) + 133.2 J/°C x (41.37°C - 25°C) = 0.496 g Mg x 24.3 g/mol x ΔH ΔH = -1714.9 J/mol