required practicals

Question 1

3 required practicals for paper 1

Answer 1

making a solution
titration
testing ions

Question 2

Making a solution method

Answer 2

• weigh sample bottle
• transfer to beaker + weigh sample bottle
• record mass difference
• 100cm3 of distilled water to beaker + glass rod to dissolve
• heat of not dissolved
• solution into 250cm3 flask through funnel
• rinse beaker + funnel + add washings from beaker to volumetric flask
• up to make with distilled water
• use pipette for last drops
• Invert flask to ensure uniform solution

Question 3

Titration equipment

Answer 3

Burette with acid
Pipette with alkali
Conical flask with distilled water

Question 4

Titration method

Answer 4

• rinse equipment
• pipette 25cm3 of alkali into conical flask
• touch surface of alkali with pipette
• add acid solution from burette
• make sure jet space is filled with acid
• add few drops of indicate + refer to colour change
• add acid to alkali whilst swirling
• note burette reading before + after acid addition
• repeat titration until 2 concordant results (0.1 difference)

Question 5

What is the phenolphthalein colour in titration?

Answer 5

Pink (alkali) to colourless (acid)

Just goes colourless

Question 6

How to work out average of titre results?

Answer 6

Only average of concordant titre results

Question 7

Recording titre results

Answer 7

Record on take in full

Record titre volumes up to 2dp (0.05cm3)

Question 8

Titration safety precautions

Answer 8

• eye protection + gloves
• conical flask as easier to swirl
• only add few drops of acid in

Question 9

What Must we consider in titration mixture?

Answer 9

It may contain other substance that have other acid base properties

Question 10

How do we know a titration mixture may contain other acid base properties?

Answer 10

Would take more acid than expected

Question 11

How to safely deal with excess acid?

Answer 11

Neutralise or wash down with water