Method

In this experiment you have two methods to choose from:

• Temperature
• Concentration

You already have access to these methods on your print outs - however please find them below for your perusal

These methods - though - are incomplete and do not account for all the control variables - factors like stirring, temperature, volume, concentration as well as correctly identifying a consistent end-point for the disappearing X and ability to start and end timing will have to be controlled during the experiment (unless they are your independent variable).

In this practice IA the Independent range has actually been defined for you - with the 5 temperatures or 5 concentrations given to you - however in an experiment where you are unsure of exactly how a trend will look or which part of the trend is most interesting to investigate you may want to attempt a Preliminary experiment.

In this experiment you could have tried a range of concentrations or temperatures - and as 5 are required to gain maximum marks for data quality the preliminary will have to be in sets of 5. i.e. 20, 35, 50, 65, 80 temperature or 10, 30, 50, 70, 90 as well as the temperatures defined in this experiment (20, 30, 40, 50, 60, 70).

After you have collected 1 set (no repeats required at this stage) you can then choose the range by selecting the temperatures which:

• Show No overlap of data
• Show data that is far enough apart to show a definite trend
• Show a trend and do not consistently plateau - If rate did not change for the last 3 temperatures then investigating these would not reveal anything particularly interesting and would be deemed a waste!
• Are safe to replicate (an example here would be carrying the experiment out at a temperature above 100 - this may evaporate the liquid)

Include these preliminary results in the Independent Variable area of the Method - include the units you will measure this in

You are unlikely to need beyond a basic stating of the Dependent variable including how you will measure it and the UNITS you will use

A number of factors can disturb rate of reaction experiments like stirring, temperature, volume, concentration as well as correctly identifying a consistent end-point for the disappearing X and ability to start and end timing will have to be controlled during the experiment (unless they are your independent variable). The thickness and size of the X will also be a control variable.

You must indicate:

• How you will control for each control variable
• The Impact of leaving the variable uncontrolled

List of apparatus including sizes, quantities, and uncertainty.

Uncertainties are to be included through all uses of any apparatus that has them.

Gives annotated and correct diagram of experimental set-up. You can take a picture of the set up using your laptops.