Question

In the lab procedure you are told to calibrate the pH meter using (1) a solution that is pH 4 and (2) a solution that is pH 7 before you measure the pH of any of the solutions that you have made. Imagine that you skip that step, you don’t calibrate the pH meter and instead you simply plug it into the LabQuest, turn it on and measure the pH of your solutions. How would that impact the following of your pH measurements?

a. Would your pH measurements be more or less precise? Why?

b. Would they be more or less accurate? Why? We would like you to think about why you need to calibrate instruments before taking measurements.

Answer 1

Calibration of the instrument is one basic and very important step before any practical or research which contains any equipment

In our case this equipment is ph metre

It is very necessary to calibrate the ph meter or any instrument otherwise we can get a consistent error in the readings and this error will affect our each and every reading

Before answering the below question lets understand what is accuracy and precision

precision-

precision is in simple words reproducibility of a result.

Or in other word precision refers to how close the values are to each other. The more they are close to each other the more they will be precise

accuracy

accuracy is degree to closeness to real value or true value .

So by keeping this in mind if we dont calibrate our ph meter and start the experiment we will get a continuous error in the experiment which will affect the accuracy throughout the experiment but it won't affect the precision since even after some error if we carried out the experiment correctly the value we get should be precise

Hence

A.ph measurents will be same precise if we dont calibrate the instrument i.e. it is unaffected

B. This will be less accurate since it will deviate from true or actual value by a error that is caused by not calibrating the ph meter

I hope this helps if you have any query or want more detailed explanation feel free to ask in the comment section below.