Making a Salt from an Insoluble Base

practical lesson 3

safety equipment and appuratus

· Safety goggles

· 250ml beaker

· 100ml beaker

· Bunsen burner, gauze and tripod

· heat resistant mat

· petri dish/watch glass

· 100ml measuring cylinder

· Evaporating basin

· Spatula and stirring rod

· Filter funnel and paper

· Tongs

· Dilute sulfuric acid

· Copper(II)oxide

first step

Wearing goggles pour about 40cm3 of dilute sulfuric acid into a beaker.

what to do after putting sulfuric acid in a beaker

Set up gauze, tripod and heat-proof mat. Using the Bunsen burner, heat the acid gently until it’s almost boiling. Turn off the Bunsen burner.

what do after switching off the bunsen burner?

Use a spatula to add a little copper oxide to the acid and stir.

after stirring the copper oxide and the acid

Keep repeating stirring the copper oxide an until the black powder does not disappear after stirring, making sure the copper oxide is in excess.

after making sure the black powder does not disappear

Filter the mixture into a beaker and pour into an evaporating basin.

after pouring into the evaporating basin

Place the evaporating basin on top of a beaker half filled with water. Heat the beaker, evaporating basin and contents using the Bunsen burner on a blue flame.

after heating using a blue flame

Heat until half the water has evaporated then allow it to cool.

after allowing it to cool

When cool transfer the solution into a petri dish or watch glass and leave for a number of days to allow the water to evaporate.

colour of the copper oxide throughout the experiment

stays black throughout the experiment because its an insolable solid

colour of the acid solution throughout the experiment

colourless throughout the experiment because dilute sulfuric acid is colourless.

colour of the solution produced in the reaction

solution produced is blue because copper sulfate dissolves in water and forms a blue solution.

why is the excess copper oxide added

make sure all the acid reacts completely, ensuring the acid is fully neutralised.

safety precaution taken with excess copper oxide added

Wear safety goggles to protect your eyes from copper oxide powder, and avoid inhaling the dust.

safety precaution for gently heating the acid

Heat the acid gently using a water bath or a low flame to avoid splashing and boiling over, and always wear safety goggles.

safety precaution taken reducing the solution by heat but allowing the last of the water to evaporate off

Heat the solution gently and carefully to avoid boiling, which can cause splashing or loss of the salt. Use a low flame or water bath and wear safety goggles.

write the word equations the you carried out

Copper oxide + sulfuric acid → copper sulfate + water

write the symbol equation that you carried out

CuO + H₂SO₄ → CuSO₄ + H₂O

what substance was left in the filter paper

excess copper oxide, which is insoluble and did not react with the acid.

what is dissolved in the solution after it is filtered

dissolved copper sulfate, which is a soluble salt formed in the reaction.

explain why is this an example of a neutralisation reaction

acid (sulfuric acid) reacts with a base (copper oxide) to form a salt (copper sulfate) and water.

Neutralisation

chemical reaction where an acid reacts with a base to form a salt and water.

substances that react with acid to form a soluable salt

metal oxide and metal carbonate

describing how to make pure, dry crystals of magnesium sulfate from a metal oxide

just describe the experiment