Heat of solution problem can't get the right answer

Question

When 2.50 g of sodium hydroxide (NaOH) was dissolved in 150.00 g of water a value of 10.50oC was obtained for ΔT.
Calculate the value (calories) for the heat of solution of 2.50 g of NaOH

Answer 1

You need to use the equation:

 

q = m*Cp* deltaT, where m is the mass of water in grams, Cp is the specific heat of water and deltaT is the change in temperature of the solution.

 

q = (150 g of water)* (4.184 J/g ºC)*(10.5ºC) = 6589.8 J

 

The problem asks for the value to be in calories, so we need to convert the Joules to calories.  The conversion you need is that 1 Joule = 0.239 calories.

 

6589.8 Joules * 0.239 cal/J = 1575 calories