Temperature Change RPA

Question 1

Method

Answer 1

1) Use measuring cylinder to measure 25 cm cubed of hydrochloric acid and add to polystyrene cup
2) use thermometer to measure temperature of acid
3) measure 5c, cubed sodium hydroxide solution, add to the acid then immediately add lid over the top
4) gently stir solution with thermometer
5) take temperature reading from thermometer when temperature stops increasing (maximum temperature reached)
6) repeat steps 1- 5, each time added 5cm cubed more of sodium hydroxide solution
7) repeat whole investigation 2 more times to calculate mean temperature for each volume of sodium hydroxide solution
8) plot graph

Question 2

2 sources of random error

Answer 2

Energy lost to surroundings (heat loss) so temperature reading on thermometer lower than it should be
Parallax error- not reading temperature on thermometer from meniscus

Question 3

How to reduce amount of heat loss to surroundings

Answer 3

Use polystyrene cup- better insulator than conical flask (reduces heat loss through sides and bottom)
Use lid (reduces heat loss by air)

Question 4

Why stir the mixture before taking temperature reading

Answer 4

To ensure the reactants have fully react and that the temperature is consistent throughout the whole mixture