Precipitation, excess reagent and titration

When do we use the excess reagent method?

soluble salt insoluble base

When do we use the titration method?

soluble salt soluble base

When do we use precipitation?

insoluble salt

What is the formula for excess reagent?

Acid + metal oxide / metal carbonate / metal / metal hydroxide

What is the formula of titration?

acid + metal hydroxide goes to salt + water

What is the formula of a precipitate reaction?

sodium salt + metal nitrate goes to sodium nitrate + metal salt

What is the method to make zinc sulphate using the excess reagent method?

Using Zinc oxide and sulfuric acid to make zinc sulphate and water
1. Put an excess of zinc oxide into sulfuric acid to ensure that all acid reacts.

2. When beaker cools reaction is complete

3. Filtering mixture of zinc sulfate and water removes insoluble reactant from salt solution

4. Zinc sulfate is left in the filter paper.

What is a precipitate

Solid substance produced rapidly as soon as 2 clear solutions are mixed.

How do we balance ionic equations?

Remove the spectator ions which don’t take part in the reaction

Method to make precipitates?

1. Add solution of metal nitrate to sodium salt solution to form precipitate

2. Filter to seperate solid

3. Wash and dry solid

Method for titration

1. Wash equipment with solutions

2. Fill burette and take readings

3. Use pipette to transfer 25cm metal hydroxide into a flask

4. Add drops of indicator and add acid from burette while swirling

5. Dropwise near reaction end point and stop when acid changes colour

6. Final reading at eye level, bottom of mensicus

7. Repeat until concordant and calculate average titre

8. Repeat without indicator and heat over a water bath evaporating water forming saturated solution

9. Cool and crystallise and filter to seperate crysals