required practicals Flashcards
required practical 4 - temperature changes
to investigate variables that affect temperature changes in chemical reactions
neutralisation between HCL and sodium hydroxide
- use a measuring cylinder to measure 30cm cubed of dilute HCL
- transfer to polystyrene cup in beaker
- measure temp using thermometer
- measure 5cm cubed of sodium hydroxide
- place in cup
- put plastic lide and thermometer through hole
- gently stir
8.measure temp change - rinse and dry cup
- repeat with more sodium hydroxide each time increase by 5 cm cubed untill 40 cm cubed
- repeat the whole experiment and calculate mean
- plot a graph
eventually max temp decreases as there is higher volume so more space for energy to spread out
polystyrene is a thermal insulator which reduces heat loss
required practical 3 - electrolysis
to investigate what happens when aqueous solutions undergo electrolysis
pour 50cm cubed of copper chloride solution into a beaker
place plastic petri dish on beaker with two holes
place carbon graphite rod into each hole
they are inert/ unreactive
must not touch eachother
add crocodile leads to rod and connect to low power suplly
cathode is coated with copper
gas bubbles at anode - chlorine gas
hold litmus paper at anode to become bleached
repeat with sodium chloride
cathode has hydrogen gas
anode has bubbles of chlorine
