EMPA Revision Book
EMPA (Unit 3) Revision Booklet
Tables
Things to always include on tasks 1 & 2:
An informative title (describe what the data shows)
Descriptive headings
The units (only one type) in the form “pulse rate /bmp”
First column containing the independent variable (the thing that is constant)
Example:
The time taken for starch to be digested by amylase at different temperatures.
Temperature /degrees C
Time taken for Digestion /s
5
115
10
101
15
85
20
75
During the data processing section, always add the mean/rate/percentage change in a different column.
When measuring variables such as pulse rate do NOT use decimals, as you can’t have half a heat beat. Think about it logically.
Calculations in Data Processing
There are three forms of processing data that depend on what data is available to when you use them.
1. The mean
This is calculated when more then one repeat has been done.
Calculate the sum of the X values and divide it by the number of X values there are. It is given by the formula:
2. Rate
This is used when you are comparing the amount produced of a substance/flow/etc. against time.
Rate = Amount produced Time Taken
It is measured in the units of the amount produced multiplied by 1/time
For example cm3min-1
3. Percentage Change * Ratios
Ratio = Value 1 Value 2
These are used when there is an increase or decrease in a variable (usually in mass). It allows a fair comparison between results, as initial values may have been different.
Standard Deviation
This measures the spread of data, and it can only be calculated when there is more than one repeat.
The larger the standard deviation, the more widely spread the data is and therefore you have a less reliable mean.
You can compare the standard deviation of two different sets of data, if the two standard deviation values
Tables
Things to always include on tasks 1 & 2:
An informative title (describe what the data shows)
Descriptive headings
The units (only one type) in the form “pulse rate /bmp”
First column containing the independent variable (the thing that is constant)
Example:
The time taken for starch to be digested by amylase at different temperatures.
Temperature /degrees C
Time taken for Digestion /s
5
115
10
101
15
85
20
75
During the data processing section, always add the mean/rate/percentage change in a different column.
When measuring variables such as pulse rate do NOT use decimals, as you can’t have half a heat beat. Think about it logically.
Calculations in Data Processing
There are three forms of processing data that depend on what data is available to when you use them.
1. The mean
This is calculated when more then one repeat has been done.
Calculate the sum of the X values and divide it by the number of X values there are. It is given by the formula:
2. Rate
This is used when you are comparing the amount produced of a substance/flow/etc. against time.
Rate = Amount produced Time Taken
It is measured in the units of the amount produced multiplied by 1/time
For example cm3min-1
3. Percentage Change * Ratios
Ratio = Value 1 Value 2
These are used when there is an increase or decrease in a variable (usually in mass). It allows a fair comparison between results, as initial values may have been different.
Standard Deviation
This measures the spread of data, and it can only be calculated when there is more than one repeat.
The larger the standard deviation, the more widely spread the data is and therefore you have a less reliable mean.
You can compare the standard deviation of two different sets of data, if the two standard deviation values