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I will provide the information needed for the tables. Must complete a post lab discussion. I can attach an example

Austin Peay State University Department of Chemistry

CHEM 1111

Measurement & Density

Introduction

Measurement is a regular part of life. For example, weight, height, and blood pressure are routinely measured in

a doctorÃ¢â‚¬â„¢s office. In the kitchen, ingredients for a recipe must be measured. Devices such as scales and measuring cups

were developed to make these measurements.

In chemistry, solutions are often used and transferred from one container to another. In some cases, it is

important to know the amount of liquid transferred with certainty, especially when performing a quantitative analysis.

Quantitative analysis is the determination of the concentration or amount of substance in a particular sample. The

certainty of a measurement is determined by looking at both the accuracy and precision of a set of measurements. While

ideal measurements should be both accurate and precise, measurements made in the lab are more often either accurate

but not precise or precise but not accurate.

Accuracy is a measure of how close a data point is to an accepted (true) value. If multiple measurements are

made of a value, then the accuracy is determined by taking the average

value and comparing it to the accepted value. The absolute error is the

difference between the accepted value and an individual measurement

% error =

measured Ã¢Ë†â€™ accepted

accepted

x 100

or average. The relative error is the absolute error divided by the accepted value. The percentage error is the relative

error multiplied by 100 %. Absolute error, relative error and percentage error are all measures of accuracy. The

percentage error is often expressed as a positive number, regardless of whether the measured value is larger or smaller

than the accepted value.

The term Ã¢â‚¬Å“precisionÃ¢â‚¬Â may be applied to either a single measurement or a group of measurements. Generally the

precision of a single measurement is simply a measure of the number of significant figures that can be expressed. Thus, a

ruler calibrated to the nearest millimeter would be more precise than a ruler calibrated to the nearest centimeter. To

express the precision of a single measurement quantitatively, the proper number of significant figures must be used.

Precision of a group of points is a measure of how close each measurement is to the others. Another way of considering

precision is to look at the range of the values; that is the difference between the highest and lowest measured values. The

smaller this range, the more precise the measurements are. In both of these definitions of precision, notice the

measurements are never compared to the accepted measured value.

When using an instrument with a digital display, write down the measurement value with the same number of

significant figures as the digital display allows. Our top-loader balances have a precision of + 0.001 g. If a mass is

displayed as 24.567 grams, this means that all but the last digit are known with certainty; last digit (7) has some degree of

uncertainty. The uncertainty in the last digit is usually assumed to be +1. However, if the balance is fluctuating in the last

two digits, then both of those numbers have error associated with them.

When reading a burette or other calibrated analog scale, the measurement should be estimated to one digit

beyond what the markings allow. Therefore, if a burette is calibrated to the nearest 0.1 mL, then the volume measurement

should be estimated to the nearest 0.01 mL. For example, if a volume measurements 11.74 mL, the 11.7 mL is known

with certainty while the 0.04 mL was estimated by the person reading the burette. Precision is often related to the person

making the measurement; very seldom do two different people make the exact same measurement every time. However,

as long as the measurement is made in a consistent manner, the precision should not be significantly affected.

In this experiment, the density of water will be measured using a burette, a graduated cylinder, a beaker and a

volumetric pipette. Based on the results, the most accurate measuring device will be determined.

Revision S20

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Austin Peay State University Department of Chemistry

CHEM 1111

Measurement & Density

Procedure

Record all measurements and unknown numbers (if given) on your data sheets. Use the proper number of significant

figures for all measurements.

Part A: Determining the Density of Water Using a Burette

A1. Obtain a burette, and fill it with deionized water using a beaker and funnel. Let the water drain through the

burette until the tip is full (the initial volume reading does NOT have to be 0.00 mL). Observe and sketch the

meniscus. Remember that measurements must always be made at the bottom of the meniscus for aqueous

solutions in glass.

A2. Obtain a 50 mL beaker. Measure and record its mass.

A3. Read and record the initial water level in the burette. Deliver approximately 15 mL of water to the preweighed beaker from the burette and read and record the final water level in the burette.

A4. Measure the mass of the beaker and water.

A5. Empty and dry the beaker.

A6. Repeat steps A2 – A5 two more times.

? Why is this process performed three times?

A7. Measure the temperature of the water.

? Why is knowing the temperature of the water important?

Part B: Determining the Density of Water Using a Graduated Cylinder

B1. Obtain a dry 100 mL graduated cylinder.

B2. Measure the mass of the empty 100-mL graduated cylinder.

B3. Add approximately 22.0 mL of deionized water to the graduated cylinder. Record the exact volume of water in

the graduated cylinder.

B4. Measure the mass of the water and 100-mL graduated cylinder.

B5. Empty and completely dry the graduated cylinder.

B6. Repeat steps B2 – B5 two more times.

B7. Measure the temperature of the water.

Part C: Determining the Density of Water Using a 50 mL Beaker

C1. Weigh a clean, dry 50 mL beaker that has graduation marks on it. Record its mass.

C2. Add approximately 20. mL of deionized water to the beaker. Record the exact volume of water in the beaker.

C3. Measure and record the mass of the filled beaker.

C4. Empty and dry the beaker.

C5. Repeat steps C1 – C4 two more times.

C6. Measure the temperature of the water.

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Austin Peay State University Department of Chemistry

CHEM 1111

Measurement & Density

Part D: Determining the Density of Water Using a 10 mL Volumetric Pipette

D1. Obtain a 50 mL beaker, measure and record its mass.

D2. Use a pipette bulb to fill the volumetric pipette to its calibration mark. The calibration mark corresponds to

10.00 mL of water being delivered from the pipette. It already takes into account that there will be a small

amount of water left in the tip, so that is not an experimental error. Empty this volume of water into the

weighed 50-mL beaker.

D3. Measure and record the mass of the beaker and water.

D4. Empty and dry the beaker.

D5. Repeat steps D1 – D4 two more times.

D6. Measure the temperature of the water.

Additional Procedural Questions

?

Why was the same procedure performed using 4 different pieces of glassware?

?

Why was water used in this experiment?

?

What is the difference between an extensive and an intensive property of a substance? State whether

mass, volume and density are extensive or intensive properties.

?

Describe two things that you learned in this lab.

Calculations

Put the results of all calculations in your lab notebook.

On a separate lab notebook page, show your calculation work for one trial of calculations A1, A2, A3, A4, A5 and A7.

A. Burette

A1. Determine the volume of water delivered by the burette in each trial by subtracting the burette readings

A2. Determine the mass of water delivered by the burette in each trial by subtracting the mass readings.

A3. For each trial calculate the experimental density of water using the mass of water delivered and the volume of

water delivered.

A4. Calculate the average density of the three trials.

A5. Calculate the standard deviation for the three trials.

A6. Using the measured temperature of the water and the reference density table, determine the accepted value

for the density of water.

**EXTRA CREDIT: Use linear interpolation to determine the density of water using the temperature measurement

to the nearest tenth of a degree.

A7. Calculate the percent error using the experimental and accepted values for the density of water.

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Austin Peay State University Department of Chemistry

CHEM 1111

Measurement & Density

B. Graduated Cylinder

B1. Determine the mass of water in each trial by subtracting the mass readings.

B2. For each trial calculate the experimental density of water using the mass of water and the volume of water.

B3. Calculate the average density of the three trials.

B4. Calculate the standard deviation for the three trials.

B5. Using the measured temperature of the water and the reference density table, determine the accepted value

for the density of water.

**EXTRA CREDIT: Use linear interpolation to determine the density of water using the temperature measurement

to the nearest tenth of a degree.

B6. Calculate the percent error using the experimental and accepted values for the density of water.

C. Beaker

C1. Determine the mass of water in each trial by subtracting the mass readings.

C2. For each trial calculate the experimental density of water using the mass of water delivered and the volume of

water delivered.

C3. Calculate the average density of the three trials.

C4. Calculate the standard deviation for the three trials.

C5. Using the measured temperature of the water and the reference density table, determine the accepted value

for the density of water.

**EXTRA CREDIT: Use linear interpolation to determine the density of water using the temperature measurement

to the nearest tenth of a degree.

C6. Calculate the percent error using the experimental and accepted values for the density of water.

D. Volumetric Pipette

D1. Determine the mass of water in each trial by subtracting

the mass readings.

Density of Water as a Function of

Temperature

o

T ( C)

Density (g/mL)

D2. For each trial calculate the experimental density of water

20

0.9982071

using the mass of water delivered and the volume of

21

0.9979955

water delivered.

22

0.9977735

D3. Calculate the average density of the three trials.

23

0.9975415

D4. Calculate the standard deviation for the three trials.

24

0.9972995

D5. Using the measured temperature of the water and the

25

0.9970479

reference density table, determine the accepted value for

26

0.9967867

the density of water.

27

0.9965162

28

0.9969748

29

0.9962365

30

0.9956502

**EXTRA CREDIT: Use linear interpolation to determine the

density of water using the temperature measurement to

the nearest tenth of a degree.

D6. Calculate the percent error using the experimental and

accepted values for the density of water.

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Austin Peay State University Department of Chemistry

CHEM 1111

Measurement & Density

Data Sheet

Make these data tables in your lab notebook.

Enter data and calculated values into the data tables in your laboratory notebook.

Make sure to label all values with units!

Part A: Determining the Density of Water Using a Burette

Trial 1

Trial 2

Trial 3

Final water level in burette

Initial water level in burette

Volume of water delivered

Mass of beaker and water

Mass of empty beaker

Mass of water delivered

Experimental density of water

Average experimental density of

water

Standard Deviation

Temperature of water

Accepted density of water from table

% Error

Part B: Determining the Density of Water Using a Graduated Cylinder

Trial 1

Trial 2

Trial 3

Measured volume of water delivered

Mass of graduated cylinder and

water

Mass of empty graduated cylinder

Mass of water delivered

Experimental density of water

Average experimental density

Standard Deviation

Temperature of water

Accepted density of water from table

% Error

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Austin Peay State University Department of Chemistry

CHEM 1111

Measurement & Density

Part C: Determining the Density of Water Using a 50 mL Beaker

Trial 1

Trial 2

Trial 3

Trial 2

Trial 3

Measured volume of water delivered

Mass of beaker and water

Mass of empty beaker

Mass of water delivered

Experimental density of water

Average experimental density

Standard Deviation

Temperature of water

Accepted density of water from table

% Error

Part D: Determining the Density of Water Using a Volumetric Pipette

Trial 1

Measured volume of water delivered

Mass of beaker and water

Mass of empty beaker

Mass of water delivered

Experimental density of water

Average experimental density

Standard Deviation

Temperature of water

Accepted density of water from table

% Error

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