Chemistry Required Practical: Rates of Reaction

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  • Created on: 19-03-19 11:01
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  • Chemistry Required Practical: Rates of Reaction
    • Method 1: Observing Colour Change
      • 1. Use a measuring cylinder to put 10cm cubed Sodium Thiosulfate solution into the conical flask. Use the measuring cylinder to then add 40cm cubed water.
        • 2. This dilutes the Sodium Thiosulfate solution to a concentration of 8 g/dm cubed. Put the conical flask on the black cross. Put 10cm cubed of dilute Hydrochloric acid into the 10cm cubed measuring cylinder.
          • 3. Put this acid into the flask. At the same time swirl the flask gently and start the stopclock.  Look down through the top of the flask. Stop the clock when you can no longer see the cross.
            • 4. Write the time it takes for the cross to disappear.  Record the time in seconds.
              • 5. Repeat steps 1?5 four times, but in step 1 use:           20cm cubed Sodium Thiosulfate + 30cm cubed water concentration 16 g/dm     cubed        30cm cubed Sodium Thiosulfate + 20cm cubed water  concentration 24 g/dm cubed        40cm cubed Sodium Thiosulfate + 10cm cubed water concentration 32 g/dm cubed          50cm cubed Sodium Thiosulfate + no water concentration 40 g/dm cubed.
                • 6. Then repeat the whole investigation (steps 1–5) twice more. Record the results.
                  • 7. Calculate the mean time for each of the Sodium Thiosulfate concentrationLeave out anomalous values from your calculations.Record the means.
    • Method 2: Measuring the Volume of Gas Produced
      • 1. Measure 50cm cubed of 2.0 M Hydrochloric acid using one of the measuring cylinders. Pour the acid into the 100cm cubed conical flask.
        • 2. Set up a clamp holding a measuring cylinder, positioned in a trough, filled with water. There should be a delivery tube leading to a conical flask, containing dilute acid plus magnesium ribbon.
          • 3. Fill the other measuring cylinder with water.  Make sure it stays filled with water when you turn it upside down.When you are ready, add a 3cm ***** of magnesium ribbon to the flask, put the bung back into the flask as quickly as you can, and start the stopclock.
    • Wear eye protection at all times.
      • Sulphur Dioxide is released during the reaction. Make sure the lab is well ventilated.
    • If using the upside down measuring cylinder filled with water, make sure there are no bubbles of air at the top.
      • Glass measuring syringes have very low friction between the inner syringe chamber and the surrounding glass. It will slide out very easily!


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