Energetics calculations

Question 1

Specifc heat capacity

Answer 1

4.2 J / g / °C

Question 2

heat energy change

Answer 2

Q = M C ΔT
q = heat energy change (J)
m = mass of solution (g)
c = specific heat capacity (usually 4.18 J g⁻¹ °C⁻¹ for water)
ΔT = temperature change = final − initial (°C)

Question 3

temperature change

Answer 3

inal − initial (°C)

Question 4

mass

Answer 4

mr x moles

Question 5

moles

Answer 5

concentration x volume

Question 6

Enthalpy change

Answer 6

Formula (from calorimetry)
ΔH = q / n
Where:
q = heat energy change (J)
n = number of moles of the substance reacting (mol)
⚠️ Convert J → kJ:
kJ= J/1000

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Question 7

Enthalpy change exothermic

Answer 7

Exothermic → energy released → ΔH is negative (−)

Question 8

Enthalpy change Endothermic

Answer 8

Endothermic → energy absorbed → ΔH is positive (+)

Question 9

decimeter conversion

Answer 9

1 dm³ = 1000 cm³

Question 10

bond energies calc

Answer 10

ΔH = reactant-product