The rock cycle describes how different kinds of rocks are formed. There is a distinctive process which explains structure of rocks. It provides insight into the particles in rocks, the rock’s hardness, colour and crystal size.
Experiment – How Crystals Grow
To simulate how rock crystals can form.
Safety glasses must be worn at all times.
• Black copper oxide (CuO) • Conical flasks Tripods
• 1 mol/L sulphuric acid (H2SO4)
• Filter paper Thermometers
• Beakers Gauze mats
• Heat source (e.g. Bunsen burners)
• Evaporating basins or small beakers
Complete the experiment by carrying out the following stages.
Add a teaspoon full amount of CuO to approximately 50mL of sulphuric acid H2SO4 in the conical flask. Swirl (do not stir with the thermometer) then heat to 70°C.
Allow to cool and filter the solution into the evaporating basin or beaker. Leave to evaporate the water on a windowsill for a period of time. If there is a lot more than 50mL, halve the solution as this will take quite a few days. The longer it takes, the larger the crystal will be.
Draw a picture of the crystals that grow.
What is the colour of the crystals? __________________________
- Complete the following word and chemical reactions for this experiment:
Copper Oxide + Sulphuric Acid —-> __________________ + Water
CuO + H2SO4 —->
(black powder) (clear liquid) ( _______ solution) + ( _______ clear liquid)
Write a conclusion about crystal growth in this experiment and how it relates to the structure of rocks. Consider
things such as:
• crystal size, shape and colour
• time to form crystals
• the relationship between crystal size and time
• rock types and crystals.