Calorimetry Question .......

[Isomer]

I'm really struggling with what to do with this question.....

 

A student designed a calorimetry experiment to determine the energy change for the following dissolving of ammonium nitrate and recorded the following results.....

 

heat capacity of calorimeter and water........................228 J / degree celsiu

initial temp of water..................................................21.6 degree celsius

final temp of water..................................................16.4 degree celsius

mass of ammonium nitrate...........................................0.250 grams

 

The amount of energy involved in this change is ____ kJ.

 

 

I've been fiddling with q = mc^t and with ^H = n^H.

 

Any ideas?? I'm not sure what to do!!!!

[swansont]

I'm not sure if your equations are actually wrong or just mistyped. (^ usually means exponent)

 

[math]Q = mc\Delta T[/math]

 

What are the relevant values of the terms?

[hybrid04]

The question is asking for kilojoules correct? The only thing you have which converts between kj and deg C is the heat capacity. That is how a calorimeter works, you take the known heat capacity of water and based on its temperature change you can determine the amount of heat put into it. Final-inital= change in temperature. Temperature times what gives you joules?

 

Side note: if the answer only asks for kJ the mass of the ammonium nitrate is moot and just there to throw you off. However if they wanted kj/gram ammonium nitrate then you would divide by the mass you added.

[Isomer]

I actually discussed this with my teacher and he said the formula to use is not q=mc^t but q=c^t. I am using this symbol ^ for delta.

 

Thanks for the responses though!