Measurement Lab

Chemcatalyst:

What types of lab equipment take measurements of substances? What is the difference between measuring precisely and accurately?

Activity:

Chemistry is based upon measuring and working with specific amounts of substances in order to see how they react with each other. Thus, it is imperative that you know how to measure both precisely and accurately. This lab is designed to review your measuring skills.

Directions: Read and follow the directions on the signs at each lab station (#1-4). Record your results in the tables below paying close attention to significant figures. Always estimate only one digit!

Volume:

Station #	Volume in mL (beaker)	Volume in mL (graduated cylinder)
1 (1 cup)	**
4 (1/4 cup)	**

Mass:

Station #	Mass in grams on digital scale #1 (g)	Mass in grams on digital scale #2 (g)
3 (weight)	**
2 (salt)	**

Data Analysis:

From your data table above, record the numbers that have an asterisk (**) in the class data table below for your group number. Then copy the rest of the class data in the table below, calculate the averages, and answer the following questions.

Station #	Group #	Avg
1	2	3	4	5	6	7	8	9	10	11
1
2
3
4

Look at the data for station #1, were the groups precise in their measurements? How do you know?

Looking at the data for station #2, were the groups precise in their measurements? How do you know?

The actual mass of the weight is 200.0 g. Look at the data for station #3, which group was the most accurate? How do you know?

Based on your answers above, what does it mean to be precise?

Based on your answers above, what does it mean to be accurate?

When measuring the volume of a liquid, which piece of lab equipment gave you the most accurate reading? How do you know?

When measuring mass, which scale gave you the most accurate measurement? How do you know?

Station #1: Volume

Use the kitchen measuring cup at this station and follow the directions below:

Fill up the kitchen measuring cup to 1 cup (water is level with the top of the cup).

Pour 1 cup of water into the glass beaker. Record your measurement in mL.

Pour 1 cup of water into the graduated cylinder. Record your measurement in mL.

Empty all containers and wait for the signal to rotate to the next lab station.

Station #4: Volume

Use the kitchen measuring cup at this station and follow the directions below:

Fill up the kitchen measuring cup to 1/4 cup (water is level with the top of the cup).

Pour 1/4 cup of water into the glass beaker. Record your measurement in mL.

Pour 1/4 cup of water into the graduated cylinder. Record your measurement in mL.

Empty all containers and wait for the signal to rotate to the next lab station.

Station #2: Mass

Use the salt and teaspoon and follow the directions below:

1. Use scale #1 to measure 1 leveled tablespoon of salt in grams. Record the weight on data table.

2. Use scale #2 to measure the 1 leveled tablespoon of salt in grams. Record on table.

3. Pour the salt back into the bag, clean off any excess salt on the scales, counter, and weight boat/paper. Leave all supplies at the station and wait for the signal to rotate to the next lab station.

Station #3: Mass

Use the golden weight and follow the directions below:

1. Use scale #1 to measure the weight in grams. Record the weight on to table.

2. Use scale #2 to measure the weight in grams. Record.

3. Leave all supplies at the station and wait for the signal to rotate to the next lab station.

Volume:

Station #	Volume in mL (beaker)	Volume in mL (graduated cylinder)
1 (1 cup)	**
4 (1/4 cup)	**

Mass:

Station #	Mass in grams (g) on scale #1	Mass in grams (g) on scale #2
3 (weight)	**
2 (salt)	**

Group Data:

Station #	Group #	Actual
1	2	3	4	5	6	7	8	9	10	11
1
2
3
4