C8 Titrations And Uses Of Acids

Question 1

Name an acidic solution found in the kitchen

Answer 1

Vinegar, fruit juice, etc.

Question 2

Name an alkaline solution used in the kitchen

Answer 2

Bleach, oven cleaner, soap, etc

Question 3

Uses of acids

Answer 3

Neutralisation, fertilisers, removal of surface dust.

Question 4

How can you prepare a soluble salt

Answer 4

A soluble salt can be prepared by reacting an acid with a soluble reactant. This is usually a dilute solution of an alkali such as sodium hydroxide or ammonia. The main steps are:

1. Carry out a titration. This is to determine the volumes of acid and alkali that must be mixed to obtain a solution containing only salt and water.
2. Mix the acid and alkali in the correct proportions, as determined in step 1.
3. Allow the water in the solution to evaporate (by heating and/or leaving for a few days) to obtain pure dry crystals of the salt.

Question 5

List Titration apparatus - draw set up (google image for set up answer)

Answer 5

. A pipette to accurately measure the volume of a reactant before transferring it to a conical flask.
. Conical flask.
. A burette to add small, measured volumes of one reactant to the other reactant.
. A suitable indicator.
. A pipette filler is needed to use a pipette safely

Question 6

Method

Answer 6

1. Use the pipette and pipette filler to add a measured volume of alkali to a clean conical flask.
2. Add a few drops of indicator and put the conical flask on a white tile.
3. Fill the burette with acid and note the starting volume.
4. Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
5. Stop adding the acid when the end-point is reached (when the indicator first permanently changes colour). Note the final volume reading.
6. Repeat steps 1 to 5 until you get concordant titres. More accurate results are obtained if acid is added drop by drop near to the end-point.

Question 7

Why is titration used?

Answer 7

Titration must be used to obtain a solution of a salt and water only, when using an acid and an alkali. This is because there is no insoluble excess reactant that could be removed by filtration.

Question 8

Titre

Answer 8

Volume of one reactant needed to react completely with the other reactant in a titration.

Question 9

Concordant tiles

Answer 9

These are titres within 0.20 cm3 (or sometimes 0.10 cm3) of each other.