Rate of Reaction Notes
Volume of gas
To find the volume of gas you must first have a full measuring tube of water then you must turn it upside down in a tray of water making sure not to lose any. Insert a tube connected to a test tube of acid and marble chips. Once you put the marble chips inside, a gas is produced. The gas will move through the tube and replace the water in the tube with gas, telling us the volume. Please note that this only works if the gas is insoluble.
When looking at the experiment we could tell that it was done because the bubbles had lessened to a stop. When looking at the graph we could tell that the experiment has stopped because it went flat meaning that the results were not changing anymore.
Average rate = Change/time for change
Mass of gas
To find the mass of gas, get a beaker and put some acid in it. Place it on a scale and put the marble chips inside. A gas will be created, (CO2) as it will be taken out of the beaker the overall mass will decrease giving us the mass of the gas.
We could tell the reaction had finished because it stopped popping, our results were getting really similar to the last minute. We could tell from the graph because it had gone flat.
Particle size
To find out how particle size affected reaction rate, we put small particles inside a beaker of acid and used a measuring cylinder to find out the volume. We were waiting for the reaction to stop.
We found that the smaller particles take less time than the bigger particles. This is because there is more surface area for it to react with.
Temperature
To find out how temperature affected reaction speeds we got different temperatures of acid and thiosulphate and placed them in a beaker over an ‘X’ on a piece of paper. The thiosulphate began to fog up the beaker making the ‘X’ not visible at the bottom of the paper. Then we knew the reaction was done.
The higher the temperature the faster the reaction. At higher temperatures the particles move faster and therefore collide more frequently. The more collisions the higher the reaction rate.
Concentration
To find out how concentration affected the rate of reaction we put equal amounts of thiosulphate and acid in a beaker. Gradually, we increase the amounts of acid and thiosulphate in the beaker.
At higher concentrations, there will be more particles buzzing around, therefore more collisions. The more collisions which occur the higher the reaction rate.
Catalysts
Catalyst is a substance that speeds up a reaction but is not used up in the reaction.
Catalysts are usually transition metals
Enzymes are a biological form of catalyst. Two examples being lactase, which breaks down lactose and pepsin which breaks down proteins.
Heterogeneous catalysts are catalysts that are a different state of matter from the reactants
Homogeneous catalysts are catalysts that are the same state of matter as the reactants.