Question

A graph with a calibration curve, linear regression and extrapolation was drawn up from your lab results. What were the two types of data that were being compared on the graph? (In other words what was on the X and Y axis) What does this graph tell you about the water sample you collected?

Answer 1

Answer:

X is the concentration of the substance being measured and Y is the response from the instrument that is being used to measure

Explanation:

A calibration curve is the plot of known concentration of substances where x is the increasing known concentration and Y is the response, typically "absorption" taken from the instrument that is used for measuring. This curve is then used to find out the concentration of the unknown substance by using it's absorbance and comparing it with the calibration curve. For example:

Concentrations and absorbance readings are as follows

0.5mg/mL=10 nm

1.0mg/mL=15nm

1.5mg/mL=20nm

2.0mg/mL=25nm

This data is plotted on a calibration curve. Next we measure the unknown substance the absorption is 20nm. We can suggest that the concentration is 1.5 mg/mL. If there are readings that fall inbetwen values then the formulat to calculate the right concentration would be y = mx + b, where m is the slope and b is the y-intercept.

Linear regression uses the modification of the slope formula y= a + bx to best see how the data of the water samples would fit on the slope of the calibration curve. X is the independent variable , b is the slope of the line and a is the y-intercept.

Extrapolation would be the action of calculating data that are outside the calibration curve,  assuming the trend would continue.