Accuracy and Precision Difference in Chemistry

In science (especially in chemistry laboratories), we depend on measurements to make observations, record results, and conclude. Two essential words will frequently arise when discussing measurements: accuracy and precision, which create confusion as sound the same, but they have different meanings and have different functions.

This page explains the difference between Accuracy and precision, which helps us to judge how correct and consistent a measurement is, with examples and tips. 

Table of Contents

• What is Accuracy?
• What is Precision?
• Distinguish Between Accuracy and Precision with Examples
• Conclusion

What is Accuracy?

Accuracy refers to how close your measured value is to the actual value. Think of it as a measure of correctness.

Let's understand it better !!

• Real-Life Example:

You're baking a cake and the recipe asks for 250g of flour. You weigh it and your scale shows 249.9g. 

That's very close to the required amount - meaning your measurement is accurate.

• A scientific example:

We know that pure water boils at 100°C. If your thermometer reads 100.1°C, we say the result is accurate because it is within a reasonable distance of the expected value. 

What is Precision?

Precision describes the degree to which you can repeat a measurement and get the same result. It does not mean that the results are correct, only that they are repeatable.

• Real-Life Example:

You weigh a packet of rice three times and get:
1)480g
2)480g
3)480g

The measurements are the same every time. So, they are precise. But if the actual weight was 500g, then while the results are precise, they are not accurate.

• Scientific Example:

A student records the boiling point of a liquid three times as:

1)103.0°C
2)103.1°C
3)103.0°C

The values are very close to one another, so they are precise. However, if the actual boiling point is 100°C, they are not accurate.

Distinguish Between Accuracy and Precision

Aspect	Accuracy	Precision
Definition	Closeness to the true value	Closeness of repeated measurements
Focus	Correctness	Consistency
Possible to Have	Without Precision	Without Accuracy
Goal in Experiments	To get correct results	To ensure reliability

Below are the illustrations that help us to understand the difference between Accuracy and Precision in a better way.

Imagine you're shooting arrows at a target:

• Accurate and Precise: All arrows hit close to the bullseye and land together.
• Accurate but Not Precise: Arrows hit around the bullseye, but are scattered.
• Precise but Not Accurate: Arrows land far from the bullseye but all together.
• Neither Accurate Nor Precise: Arrows are scattered and far from the bullseye.

Conclusion

Distinguishing between accuracy and precision is helpful when interpreting scientific data, and both are important in chemistry. When practical, we want our results to be accurate so that they are meaningful, and precise so that they are repeatable. 

Keep these two ideas in mind, and whether you are experimenting with a classroom or analysing data in real life, you will become a more thoughtful and accurate observer!