Practical 7b

• One of the products can be collected using a gas syringe. State the name of the product and draw a diagram of the apparatus.

  Hydrogen gas
• Outline a method to determine the initial rate of reaction.

  > Set up the apparatus, conical flask connected to a gas syringe

  > Add 25 cm3 of 1 mol dm-3 hydrochloric acid measured using a measuring cylinder to a conical flask

  > Add a 6 cm strip of magnesium to the acid in the conical flask and immediately connect the gas syringe, and start the timer

  > Record the volume of gas collected every 30 seconds up to 3 minutes

  > Plot a graph of volume of hydrogen (cm3) against time (s)

  > Draw a tangent at t=0 and calculate the gradient
• If the concentration of dilute hydrochloric acid was halved, how would this affect the initial rate of reaction and explain why.

  If the concentration of the dilute hydrochloric acid was halved, the rate of reaction would decrease. This is because there are less particles of reactants, therefore, less successful collisions per unit time.