Chemistry Practicals: Salt Making, Temperature Changes & Electrolysis
Making copper sulphate crystals is straightforward once you get the method down. Start by measuring 50cm³ of sulphuric acid, pour it into a beaker, and gently heat it. Then add copper oxide (a solid base) in excess - this ensures all the acid gets used up and you'll see the mixture turn blue.
Filter out the excess copper oxide using filter paper, then gently heat your blue solution until it evaporates. You'll watch copper sulphate crystals form right before your eyes! The key trick here is slower evaporation creates bigger crystals, so don't rush the heating process.
For temperature change experiments, you'll measure how different metals react with copper sulphate solution. Set up a polystyrene cup with 30cm³ of copper sulphate, measure the starting temperature, then quickly add 5g of magnesium and cover with a lid to prevent heat loss. Record the maximum temperature change, then repeat with iron and tin to compare results.
Top Tip: Always record your results immediately and draw graphs to spot patterns - this makes it much easier to explain what's happening in your write-ups.
Electrolysis demonstrates how electricity splits compounds apart. Set up 50cm³ of sodium chloride solution in a beaker with two carbon graphite electrodes (they're inert, so won't interfere). Connect to a low voltage power supply and watch the magic happen - hydrogen gas bubbles at the cathode, whilst chlorine gas forms at the anode and bleaches damp blue litmus paper.
Remember your safety precautions: goggles, proper ventilation, tie back long hair, and turn off Bunsen burners when not in use. These experiments involve acids, heat, and toxic gases, so taking safety seriously isn't optional.
