Amount Of Substance

Question 1

Volumetric solution
Transfer known mass of solid (1)

Answer 1

Place weighing boat on balance and tare
Transfer solid to weighing boat
Record mass

Question 2

Volumetric solution
Dissolve in water (2)

Answer 2

Transfer solid to beaker rinse boat with deionised water into beaker
Add approx 100cm3 of deionised water to beaker
Stir with glass rod until dissolved

Question 3

Volumetric solution
Transfer and washing (3)

Answer 3

Transfer solution to volumetric flask using funnel
Rinse beaker, rod and funnel with deionised water into the flask
Add deionised water up to graduation mark on flask with a dropping pipette
Invert flask to make sure fully mixed

Question 4

Phenolphthalein

Answer 4

In acid - colourless
In alkali - pink

Question 5

Methyl orange

Answer 5

In acid - red
In alkali - yellow

Question 6

Rough titration

Answer 6

1) rinse burette with deionised water, rinse with standard solution
Fill burette (and tap) with standard solution - take reading to 2 d.p

2) rinse pipette with deionised water and then with unknown solution
Transfer 25 cm3 of unknown solution to conical flask with pipette

3) add 3 drops of indicator to conical flask and place under burette

4) add solution from burette constantly swirling conical flask until colour change occurs

5) write final burette reading to 2 d.p

6) empty conical and rinse with deionised water
Refill burette

Question 7

Subsequent titration

Answer 7

1) Add 2 cm3 less than rough titre value to conical flask

2) wash sides of flask with deionised water to ensure all reagent is reacting
Add drop wise and swirl until endpoint is reached

Continue titration until you have concordant values