Temperature changes

Question 1

Method for required practical temperature changes

Answer 1

Add 25.0 cm3 of sodium hydroxide into a polystyrene cup, place polystyrene cup into a beaker to stop the cup falling over, record temperature of the NaOH after 1 minute, add 5 cm3 hydrochloric acid to polystyrene cup, add plastic lid to cup to reduce energy loss, Use thermometer to stir reactants to ensure the reactants mix, record temperature, repeat experiment from steps 4 to 6

Question 2

How to draw graph for required practical temperature change

Answer 2

X-axis - vol of HCl cm3
Y- axis - temperature°C
1st straight line = increasing temp
2nd straight line = decreasing temp
extend both lines till they meet this is the volume of HCl needed to neutralise 25.0 cm3 of NaOH

Question 3

Required practical temperature changes - why is the lid needed

Answer 3

reduces energy loss into the surroundings

Question 4

Required practical temperature changes - why does the temperature fall towards the end

Answer 4

after all the acid has been neutralised the colder sodium hydroxide will lower the overall temperature of the reaction mixture

Question 5

Required practical temperature changes - how could the experiment be improved

Answer 5

digital temperature probe

Question 6

Required practical temperature changes - how else could we reduce energy loss

Answer 6

pack cotton wool around the cup