# Question Video: Selecting the Most Accurate Piece of Glassware Chemistry

The picture shows the top parts of several graduated cylinders. Which of the following graduated cylinders can give the most accurate measurement? [A] Graduated cylinder A [B] Graduated cylinder B [C] Graduated cylinder C [D] Graduated cylinder D

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### Video Transcript

The picture below shows the top parts of several graduated cylinders. Which of the following graduated cylinders can give the most accurate measurement?

Accuracy describes how close a measurement is to a true or accepted value. So the most accurate measurement will be the measurement that is the closest to the true value. To help us determine which of the graduated cylinders can give the most accurate measurement, let’s assume that each of the graduated cylinders is the same size. This means that the only difference between the graduated cylinders is the number of markings or graduations they have.

Three of the markings are in the same location on all four graduated cylinders. Let’s assign these markings the values 12, 16, and 20 milliliters to make the graduated cylinders easier to compare. To each of the graduated cylinders we’ll add exactly 17.3 milliliters of water. This will represent the true value. When water is added to a graduated cylinder, the surface of the water tends to curve downwards. This is due to the surface tension of the water and the adhesive forces between the water molecules and the glass. The curvature of a liquid surface is called the meniscus. For simplicity, the surface of the water in each of these graduated cylinders is shown as a straight line rather than as a curve. Let’s see what the markings provided on each graduated cylinder can tell us about the volume of water contained.

Looking at graduated cylinder (A), we can see that the volume of water is between 16 and 20 milliliters. We can also see on graduated cylinder (B) that the volume is between 16 and 20 milliliters. But because there are more markings, we can narrow down this range even further. The graduations on this graduated cylinder increase by 0.5 milliliters. So we can see that the volume of water is between 17 and 17 and a half milliliters. The graduations on graduated cylinder (C) increase by two milliliters. So we know the volume of water is between 16 and 18 milliliters. The graduations on graduated cylinder (D) each increase by one milliliter. So we know the volume of water is between 17 and 18 milliliters.

We can see that graduated cylinder (B) has the smallest error margin. This means that using graduated cylinder (B) will produce measurements that are the closest to the true value. Therefore, the graduated cylinder that can give the most accurate measurement is the graduated cylinder that has the most graduations, in this case graduated cylinder (B).