Practical Skills

Question 1

How do you make up a volumetric solution

Answer 1

Work out how many moles are needed to make the solution
Calculate the mass needed to make up this amount of moles
Weigh beaker
Then add the solid into the beaker
Work out the mass(difference)
Add distilled water
Stir
Funnel to our it into 250cm3 volumetric flask
Rinse beaker with distilled water and put it into the flask
Add distilled water up to the miniscus of the volumetric flask
Using mass calculate new concentration of solution

Question 2

How do you do an acid based titration

Answer 2

Pipette known volume of unknown solution in 25cm3 conical flask
Add few drops of indicator
Add volumetric solution to the Burette with a funnel
Record start volume
Titration from Brett’s into conical flask until the solution changes colour
Record vol in Burette
Repeat until concordat results
Calculate an average titre

Question 3

What indicators could you use in a titration and what colours are they in what conditions

Answer 3

Phenolphthalein
Pink in alkali and colourless in acidic

Methyl orange
Reddish in acid and yellow in alkali

Question 4

How do you measure enthalpy change

Answer 4

Calorimetry

Question 5

Experiment for enthalpy of combustion

Answer 5

With a bomb calorimeter 
Weigh fuel before 
Burn fuel to heat Water 
Read the starting temperature 
Then measure the final temperature 
Reweigh the fuel 
Calculate moles

Question 6

Experiment for enthalpy of neutralisation

Answer 6

Add known vol of acid and alkali to polystyrene cup
Thermometer measure temp change
Stir solution to ensure mixing

Question 7

Experiment for enthalpy of dissolution

Answer 7

Add solid to water and dissolve

Question 8

Displacement?

Answer 8

Add metal to salt solution

Question 9

General problems with Calorimetry

Answer 9

Heat loss - insulation