If 5g grams Urea is dissolved in 10mL water, what is the temperature change? We are not given any constants as we are meant to research. Here is what I think I have to do: Calculate enthalpy of solution of urea. That is, enthalpy of hydration - lattice energy of urea. Then I multiply this by the number of moles of Urea (mass divided by RMM) to get the total enthalpy change. After this step I have a problem. With just water I could isolate ΔΤ in Q=mCΔΤ, although here I am dealing with a mixture of Urea and water, so the heat capacity value is inaccurate. If I had equal quantities (in moles) of Urea and water could I average the heat capacity of both and use that (and thus use the ratio between the moles of urea and water to work something out in this scenario)? Or have I done something completely wrong to begin with?