long answer questions

Question 1

how can you obtain a soluble salt (crystals) from an acid and insoluble base?

Answer 1

1. heat acid in water bath
2. add insoluble base to acid until in excess and solid starts to sink to bottom
3. filter off solid to obtain the solution containing only salt water
4. heat solution using bunsen burner so water can evaporate, then leave solution to cool and cystallise
5. filter off solid and leave to dry in warm oven

Question 2

how can you obtain an insoluble salt by mixing two soluble salts together?
USING LEAD SULFATE AS AN EXAMPLE

Answer 2

1. add LEAD NITRATE (SOLUBLE) into a test tube and water to dissolve it, then do the same with MAGNESIUM SULFATE (SOLUBLE)
2. tip solutions into a beaker and stir, LEAD SULFATE should precipitate out
3. filter into conical flask
4. pour in contents from beaker and swirl with deionised water
5. rinse contents in filter paper and wash with deionised water so all MAGNESIUM NITRATE is washed away
6. leave LEAD SULFATE to dry in warm oven

Question 3

how to perform a titration (an acid and alkali)?

Answer 3

1. add 25cm cubed of alkali to conical flask and add a few drops of indicator
2. fill burette with acid and add to alkali slowly, swirl conical flask
3. indicator changes colour when neutralisation has happened, record volume of acid needed to neutralise alkali