4.3 Enthalpy change RP

Question 1

Calculate energy change from a calorimetry experiment equation

Answer 1

q = mcΔT

Question 2

what is each symbol for in the energy change in calorimetry equation? (+units)

Answer 2

q = energy (in J)
m = mass of water (in g)
c = specific heat capacity
ΔT = temperature change ( in o C or K, don’t need to convert)

Question 3

Calculate enthalpy change from a calorimetry experiment

Answer 3

ΔH = q / moles reacted (smallest number of moles present)

Question 4

Explain why calculations from calorimetry experiments are often
lower than theoretical values

Answer 4

• heat lost to the surroundings
• incomplete combustion (of fuels)
• evaporation (of fuels)

Question 5

How can you improve accuracy of calorimetry experiments due to heat
loss?

Answer 5

• better insulation
• heat shield (for fuels)

Question 6

How should temperature change for a calorimetry experiment for
an aqueous reaction be calculated?

Answer 6

• measure start temperature every minute for 4 mins
• mix reactants
• record temperature every minute for 10 mins
• plot a graph and regress line of temperature change to find ΔT