Calorimeter question?

[Starlight]

The heat of solution of sodium nitrate can be determined using a simple coffee cup calorimeter. 0.0020 mol of solid NaNO3 is dissolved in water to make 100g of solution. The temperature of the solution decreased by 0.1005degrees celsius. Assuming that the specific heat capacity of the solution of 4.18Jperdegreecelsiusperg. The enthalpy change for this reaction in Kjpermol of NaNO3 is closest to:

a) +21
b) -21
c) +42
d) -42

Apparently answer is a?

[Destiny]

I've never heard of enthalpy.  Are you sure it's in the study design?  Sounds like Unit 4.

[Lasercookie]

I've never heard of enthalpy.  Are you sure it's in the study design?  Sounds like Unit 4.

It is in Unit 4, but I believe El2012 does the VCE Chem equivalent subject at uni.

[Starlight]

It's ok I found the solution actually!