Required Practical 4: Temperature Changes

Investigating the temperature change of a neutralisation reaction and how the temperature changes depending on the amount of a reactant.

Hydrochloric acid + Sodium Hydroxide —> Sodium Chloride + Water (exothermic)

IV: Volume of sodium hydroxide

DV: Maximum temperature reached by the solution

CV: Volume of hydrochloric acid, Concentration of sodium hydroxide and hydrochloric acid

Method:

  • Measure 30cm3 of dilute hydrochloric acid using a measuring cylinder

  • Transfer acid into a polystyrene cup as the cup is a good thermal insulator

  • Stand cup in a beaker to stop cup falling over

  • Use thermometer to measure temperature of the acid

  • Measure 5cm3 of sodium hydroxide

  • Add to the cup then place a lid after with a hold for the thermometer to still fit through

  • Use the thermometer to gently stir the solution and then read the thermometer until the highest temperature possible is seen and then is recorded.

  • Repeat experiment by adding another 5cm3 of sodium hydroxide each time until 40cm3 is reached.

  • Repeat the whole experiment again to find the mean temperature of each volume of sodium hydroxide

  • plot graph as seen below

Result:

Beginning: As more sodium hydroxide is added, the maximum temperature reached increases because there are more particles of sodium hydroxide there to react with the hydrochloric acid

Arrow on diagram: The point where the maximum temperature reached is the highest, will be when the volume of the two solution is the same (if both concentrations are equal)

End: Temperature starts to decrease as there is too much sodium hydroxide so the hydrochloric acid cannot react with all of it. Furthermore, there is a greater volume of solution with each experiment so the thermal energy released is spread out into a greater volume so the maximum temperature actually decreases instead of remaining stagnant.