$\frac{24.5 - 25.0}{25.0} \times 100 = -2\%$ (absolute value = 2\%)

$\frac{\text{Experimental} - \text{Actual}}{\text{Actual}} \times 100$

$\frac{10 - 25}{25} \times 100 = -60\%$

Question 1

Which laboratory glassware would be most appropriate for preparing a solution that requires the highest accuracy in volume measurement?

Accepted Answer

Volumetric flask

Question 2

A student needs to transfer 5.0 mL of a liquid as accurately as possible. Which tool should they use?

Accepted Answer

Pipette

Question 3

When reading the volume of a liquid in a graduated cylinder, what is the correct way to read the meniscus?

Accepted Answer

At the bottom of the meniscus, eye level with the cylinder

Question 4

Which of the following best describes the difference between accuracy and precision?

Accepted Answer

Accuracy is how close measurements are to the true value; precision is how close measurements are to each other.

Question 5

A student measures the mass of a sample three times and records: 5.1 g, 5.2 g, and 5.1 g. The true mass is 5.0 g. Which statement is correct?

Accepted Answer

The measurements are precise but not accurate.

Question 6

Which of the following is an example of a systematic error?

Accepted Answer

A balance that is not zeroed before use

Question 7

Calculate the percent error if the experimental value is 24.5 g and the actual value is 25.0 g.

Accepted Answer

$\frac{24.5 - 25.0}{25.0} 	imes 100 = -2\%$ (absolute value = 2\%)

Question 8

Which of the following best describes a random error?

Accepted Answer

An unpredictable error that varies in magnitude and direction

Question 9

A student records the following masses for a 50.0 g standard: 49.8 g, 50.1 g, 50.2 g, 49.9 g. What can be said about the accuracy and precision?

Accepted Answer

High accuracy, low precision

Question 10

Which of the following is the correct number of significant figures in the measurement 0.02030 g?

Accepted Answer

5

Question 11

When adding 12.34 g and 0.6 g, what is the correct answer with the proper number of significant figures?

Accepted Answer

$12.9\ \mathrm{g}$

Question 12

Which of the following best describes the proper use of a burette?

Accepted Answer

Used to measure and deliver variable volumes of liquid accurately

Question 13

A student is titrating an acid with a base. Which piece of glassware should be used to deliver the base accurately?

Accepted Answer

Burette

Question 14

Which of the following is NOT a source of systematic error?

Accepted Answer

Random fluctuations in room temperature

Question 15

If a student consistently reads the meniscus from above rather than at eye level, what type of error is introduced?

Accepted Answer

Systematic error

Question 16

Which of the following is the correct formula for percent error?

Accepted Answer

$\frac{	ext{Experimental} - 	ext{Actual}}{	ext{Actual}} 	imes 100$

Question 17

A student performed a chemical reaction and obtained 10 g of product. The theoretical yield was 25 g. What is the percent error?

Accepted Answer

$\frac{10 - 25}{25} 	imes 100 = -60\%$

Question 18

Which of the following best describes the use of a graduated cylinder?

Accepted Answer

Used for measuring approximate volumes of liquids

Question 19

Which of the following is the best practice when measuring mass using a balance?

Accepted Answer

Use a weighing paper or container and tare the balance before adding the chemical

Laboratory Techniques, Measurement, and Error Analysis in General Chemistry

Study Guide - Practice Questions