rq 4: temp changes

Equipment list

• 2 M hydrochloric acid
• 2 M sodium hydroxide solution
• Expanded polystyrene cups and lids with thermometer holes

Thermometers Method

1. Measure 25cm3    of hydrochloric acid into a polystyrene cup.
2. Place the cup inside the beaker to make it more stable.
3. Measure and record the temperature of the hydrochloric acid.
4. Measure 5cm3    of sodium hydroxide and add it to the polystyrene cup.
5. Quickly put a lid on the cup and gently stir the solution with the thermometer through the    hole of lid.
6. When the reading on the thermometer stops changing and becomes fairly constant,    record the temperature.
7. Repeat steps 4 and 5 to add further 5 cm3    amounts of sodium hydroxide to the cup. A    minimum total of 40 cm3    needs to be added.
8. Repeat steps 1–7 to ensure reliability of results.
9. Calculate the mean maximum temperature reached for each of the sodium hydroxide    volumes