Formulas

Question 1

What is the formula for determining change in thermal energy?

Answer 1

Q = mcΔt

where:
m = mass (g)
c = heat capacity (J/g‧˚C)
Δt = change in temperature (˚C)

Question 2

What is the formula for calculation enthalpy changes?

Answer 2

Molar enthalpy, in kJ/mol, and the number of moles of a substance can be used to calculate the enthalpy change of a chemical change:
ΔᵣH = nᵣH
ΔᵣH = enthalpy changes in kJ (or J)
n = number of moles in mol
ᵣH = molar enthalpy in kJ/mol or J/mol

the number of moles can either come from the balancing in the chemical reaction of from the formula n=m/M
always have a sign on ΔH (or H)
positive for endothermic (energy absorbed)
negative for exothermic (energy released)