2) The concentration of a reaction is proportional to the concentration of the acid used.
3) Pressure increases the rate of reactions due to the molecules being more compressed, making them react more rapidly.
4) Temperature affects the rate of reactions by giving ions more kinetic energy. Due to there being an increase in temperature causing more vigorous collisions between the particles. In turn giving them a greater chance of reacting together.
5) A catalyst speeds up reactions without having any change of its own. It remains unchanged throughout the reaction and does not interfere with the reaction. They enable a reaction to take place more rapidly or enable a reaction to take place at a lower temperature.
Changed variables: the volume of acid used and the time taken to collect 50ml of gas.
Constant variables: the concentration of the acid and the amount of marble chips used
Prediction: when reacting marble chips with hydrochloric acid, I predict that the greater the volume of acid that is used at a constant concentration, the greater the amount of gas will be given off in a shorter amount of time.
Apparatus:
Conical flask
Delivery tube
Measuring cylinder
Water basin
Stop watch/ stop clock
Rubber bung
Hydrochloric acid
Marble chips
Water
Diagram:
Method:
1) Set up the apparatus as shown above
2) Produce adequate results table as shown over-leaf
3) Half fill a basin with cold water
4) Place water filled measuring cylinder face down upright in the water for measuring the amount of gas given off.
5) Accurately measure out 1.0g of marble chips
6) In a conical flask add 10cm³ of 1.0M concentration of hydrochloric acid
7) Carefully attach the delivery tube underneath the water filled measuring cylinder (making sure all the water remains in the cylinder)
8) Put the other end of the delivery tube in a rubber bung.
9) Carefully add the marble chips to the conical flask containing the hydrochloric acid, careful not to spill any of the marble chips.
10) Attach the bung to the top of the conical flask and quickly start the stopwatch.
11) Record on the table the time taken to collect 50ml of gas in the test tube.
12) Repeat steps 4 to 11 until you have collected an efficient amount of results then record your finding on a graph.
Results table:
Conclusion: my results show a pattern similar to that of my prediction. If I was to repeat this experiment then I would use the volume of acid in multiples of 5 and I would do the experiment twice as to produce a fair test.