1)When a 9.55 g- sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 23.6 C to 47.4 C .
Calculate the molar enthalpy (in kJ/mol NaOH) for the solution process NaOH(s)>>Na+(aq)+OH-(aq) . Assume that the specific heat of the solution is the same as that of pure water.
2)A 2.300 g sample of quinone (C6H4O2) is burned in a bomb calorimeter whose total heat capacity is 7.854 kJ/C. The temperature of the calorimeter increases from 23.90C to 31.35C.
- What is the heat of combustion per gram of quinone?
- What is the heat of combustion per mole of quinone?
1) We need to assume that the heat yielded by dissovling NaOH is absorbed by the solution.
so first calculate the heat absorbed by the solution:
Q = mc * deltaT.
where the mass of the solution = 9.55 + 100.0 = 109.55 grams.
the specific heat of pure water c = 4.184 J/(g.K)
the temperature change ...
It shows how to calculate the molar enthalpy during hydroxide dissolving process. It also calculates the heat from the combustion of quinone.