When 1.50g of magnesium metal is allowed to react with 200mL of 6.00M aqueous HC

Question

When 1.50g of magnesium metal is allowed to react with 200mL of 6.00M aqueous HCl, the temperature rises from 25.0 degrees Celsius to 42.9 degrees Celsius. Calculate delta H (in kilojoules) for the reaction, assuming that the heat capacity of the calorimeter is 776 Joules/degrees celsius, that the specific heat of the final solution is the same as that of water (4.18J/g degrees celsius), and that the density of the solution is 1.00 g/mL.

I'm stuck because I'm not sure what equation for delta H to use. I thought it would be equal to q, but I'm not sure how to go about that either.

Explanation / Answer

Mg + 2 HCl -------------> MgCl2 + H2

ASthis reaction goes on heat evolved in this reaction will goes to rise Temperature of calorimeter and of products.

so heat absorbed by calorimeter= 776*(42.9 -25 ) =13.89 KJ

heat absorbed by mixture = 4.18*(42.9-25)*m

where m is the mass of the solution

m=1.50 + 0.200*6*36.5 =45.3 g

heat absorbed by mixture = 4.18*(42.9-25)*45.3 =3.38 KJ

so total heat evolved =3.38 + 13.89 =17.27 KJ

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