(P)Precipitation & Colour Change

• 1. You can record the visual change in a reaction if the initial solution is transparent and the product is a precipitate which clouds the solution
• 2. You can observe a mark through the solution and measure how long it takes for it to disappear - the faster the mark disappears, the quicker the reaction
• 3. If the reactants are coloured and the products are colourless (or vice versa), you can time how long it takes for the solution to lose (or gain) its colour
• 4. The results are very subjective - different people might not agree over the exact point when the mark 'disappears' or the solution changes colour.
• 5. If you use this method, you can't plot a rate of reaction graph from the results
• A more scientific way of saying that the cloudiness of a solution changes is to day that its 'turbidity' changes