Practicals

Question 1

Melting point apparatus

Question 2

Colorimetry

Answer 2

Set complementary colour filter
Zero with a cuvette of distilled water
Make up dilution series with known concentrations
Measure absorbance of the solutions
Plot a graph of absorbance against concentration
Draw a line of best fit
Use graph to read concentration of that absorbance

Question 3

Recrystallisation

Answer 3

Choose a solvent where the product is more soluble at a high temperature
Dissolve solid in a minimum amount of hot solvent
Filter when hot to remove insoluble impurities
Leave to cool
Filter of crystals
Soluble impurities are left in filtrate
Wash with cold solvent and dry

Question 4

Q=mct practical

Answer 4

Overview: measure temperature increase of water/burning fuel under a container of water
Measure water using measuring cylinder
Polystyrene/insulated cup
stir to improve heat distribution
Ensure thermometer isn’t in contact with the bottom of the beaker
Use draught excluders
Use lid to prevent heat loss and stop evaporation
Measure initial temperature
Add solid and measure final temperature when solid has fully dissolved

Question 5

Titration practical

Answer 5

Pipette 25cm3 into suitable flask
Add indicator
Place acid/alkali into burette
Rinse pipette/burette with solution to be delivered
Titrate until colour change
Repeat until titre is concordant
Add dropwise near to endpoint

Question 6

How to make a standard solution