Delta Fares

Enthalpy Change in Delta H of a Unknown Substance? I Need Help Please.?

A calorimeter contains 26.0 ml of water at 12.5 degree C. When 1.30 g of X (a substance with a molar mass of 66.0 ) is added, it dissolves via the reaction X(s)+H20(l)=X(aq) and the temperature of the solution increases to 28.5 degree C. Calculate the enthalpy change,delta H , for this reaction per mole of X. Assume that the specific heat and density of the resulting solution are equal to those of water [4.18 J/(gxC) and 1.00 g/ml ] and that no heat is lost to the calorimeter itself, nor to the surroundings. Express your answer numerically in kilojoules per mole.

Public Comments

1. for this you use the formula Q=MCdeltaT This means that the heat is equal to the grams of the substance x the specific heat x the change in the temperature. The heat is then equal to the delta h. So: Q = (1.30 g + 66.0 g)(4.18)(28.5-12.5) Q = (67.3)(4.18)(16) so Q = 4501.024 J Then convert to KJ (there are 1000 J in one KJ) SO it is 4.50 KJ