Materials Included In Kit

Additional Materials Required

Prelab Preparation

1. Position a heat lamp 30 cm from the surface of a lab table for use in the temperature measurement activity. The lamp may be attached to a ring stand.
2. Color isopropyl alcohol and sodium chloride solutions so they may be easily identified to pour pack in the original container. This will help prevent contamination due to students returning the chemical to the wrong bottle.

Safety Precautions

Isopropyl alcohol is a moderate fire risk and slightly toxic by ingestion or inhalation. Use extreme caution while using heating equipment. Lamps and bulbs can get very hot and cause burns. Do not leave the lamps unattended. Wear chemical splash goggles. Wash hands thoroughly with soap and water before leaving the laboratory. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. All solid wastes in this lab may be disposed of according to Flinn Suggested Disposal Method #26a, in the regular trash. Isopropyl alcohol may be disposed of according to Flinn Suggested Disposal Method #18a. All other liquid wastes in this lab may be disposed of according to Flinn Suggested Disposal Method #26b, flushed down the drain with an excess of water.

Lab Hints

• Enough materials are provided in this kit for 30 students working in pairs or for 15 groups of students. This laboratory activity can reasonably be broken into parts and completed in any order. Ideally, the entire activity can be completed in two 50-minute class periods.
• Many of the materials may be reused, such as plastic cups, medicine cups and pipets, and should be rinsed and dried between each part of the lab.
• The isopropyl alcohol and sodium chloride solutions may be colored for easy identification. Students may use the solutions and return them to their bottles.

Teacher Tips

• The activities in this kit may be performed in any order and may be used as an introduction to measurement, a review of measurement or as stand-alone activities as each type of measurement is discussed throughout the school year.
• Use the concentration activity to discuss the effects of pollutants on the environment.
• The density of the screw may also be determined.
• The curved surface of a liquid in a graduated cylinder is called the meniscus. Volume should be read using the bottom of this curve as seen in Figure 2.
  {13553_Tips_Figure_2}
• Before lab help students figure out how to enter data for Activity 6. Explain cup 1 containing 9 mL of water and 1 mL of dye is 10% red dye. Then explain that would be 100,000 ppm because 1,000,000 x 0.1 = 100,000.

Answers to Prelab Questions

1. What instruments may be used to measure each of the following quantities?
   1. Length

      Metric ruler, tape measure or meter sticks may be used to measure the length of objects.

   2. Mass

      A balance may be used to measure the mass of an object.

   3. Volume

      A graduated cylinder may be used to measure the volume of an irregular solid or a liquid. The volume of a regular solid may be measured using a ruler or tape measure.

   4. Temperature

      The temperature of an object may be measured using a thermometer.

2. What is density?

   Density is the mass of an object per unit volume and may be calculated using the formula density = mass/volume.

3. How might the concentration of a substance affect its ability to harm an organism?

   A toxin with a higher concentration is more likely to harm an organism than a lower concentration.

Sample Data

Activity 1. Measuring Length

Activity 2. Measuring Volume Activity 3. Measuring Mass Activity 4. Determining Density Activity 5. Measuring Temperature Activity 6. Measuring Low Concentrations of Water Pollutants

Answers to Questions

1. Convert the data from Activity 1 from millimeters to centimeters and meters. Record answers in the Activity 1 data table of the worksheet.

   See Activity 1 data table.

2. Convert the data from Activity 2 to microliters and liters. Record answers in the Activity 2 data table.
3. Convert the length measurements of the textbook in Activity 1 to volume by multiplying length, width and height. Record the answer in cubic centimeters.

   26.2 cm x 21.1 cm x 2.9 cm = 1603.2 cm³ Student answers may vary depending on the book measured.

4. Calculate the density of each liquid in Activity 4 by dividing the mass by volume. Record the values in the Activity 4 data table on the worksheet.

   See Activity 4 data table.

5. In Activity 3 the mass of 100-mL of water was determined. Using this data, calculate the density of the water. Note: Give answer in either g/mL of g/cm³.

   100.14g/100mL = 1.00 g/mL of 1.00 g/cm

6. How does the density of water calculated in Question 5 compare to the density value obtained in Activity 4?

   Regardless of the volume or method used to obtain the density the density of water should be the same in both activities as the density of water is 1.00 g/cm³.

7. Which liquid in Activity 4 has a greater density than water? Which liquid has a density less than water?

   The salt water has greater density than water and the isopropyl alcohol is less dense than water.

8. In Activity 5 the temperature of two different colors of sand, black and white, were compared. Using the data from Activity 5, graph the temperature values for the 8-minute exposure of each color of sand. Note: Graph both sand colors on the same graph using a different colored pen or pencil for each. Use the horizontal (x) axis for the time and vertical (y) for the temperature. Label each axis—do not forget the units—make sure the scale is clearly marked. Draw a best fit line for each color of sand through the data points for each sand color.
   {13553_Answers_Figure_3}
9. Compare and contrast the temperature change of each color sand after 8 minutes. Explain the difference.

   After 8 minutes the black sand had the greatest temperature change starting at 22 °C and ending at 30 °C. The temperature increased 8 °C over the 8 minutes. The temperature of the white sand increased 4 °C over the same time period. This is because darker colors absorb more heat than lighter colors.

10. Determine the percent red solution and parts per million of red solution in each cup. Record in the data table on the worksheet.

    See Activity 6 data table.

11. Janet received a small fish tank for her birthday. However, it did not say how many liters of water it holds. Based on the measurement methods in this lab name two ways Janet could figure out how many liters of water her fish tank holds.

    Janet could determine how much water her fish tank holds by the direct method of measuring the water in a beaker or graduated cylinder or by measuring the length, width and height and multiplying these together. She would then convert cm³ to mL and finally to liters.

Introduction

Measurement is a basic and essential component in any science laboratory investigation. Quantitative measurement is important in any society and the standardization of measurement units has become extremely important as a result of globalization.

Concepts

• Concentration
• Measuring skills
• Density
• International System of Units (SI)

Background

In order to interpret data and draw conclusions, the precise measurement of results is essential in most laboratory investigations. In any science classroom, students use basic scientific instrumentation to measure properties of objects. Measurements include those for mass, volume, length, temperature and density.

The world around us may be examined either quantitatively or qualitatively. A qualitative observation is one that describes the characteristics or attributes of an object. “The table is black” or “the pencil is short” are qualitative observations. Quantitative observations are those that are measured. “The pencil has a mass of 5.4 g” or “the table is 2.1 m long” are quantitative observations.

Because the scientific method requires an experiment to be repeatable, observations and results must be reported quantitatively. In a science laboratory, the system of measurement used to make quantitative measurements is the International System of Units (SI), also known as the metric system. It is necessary to understand SI for performing many scientific activities.

SI uses units based on the number ten. It is very easy to change one unit into another by dividing or multiplying the unit by 10 or a multiple of 10. The meter (m) is used for length, the liter (L) is used for volume, the gram (g) is used for mass and the degree Celsius (°C) is used for temperature. The following prefixes may be used with each unit.

Length is a straight-line measurement of an object from one end to the other. The standard unit for length is the meter (m) and the most commonly used units for length include the millimeter, centimeter, meter and kilometer. The conversions may be calculated using the chart above. For example, there are 1000 millimeters (mm) in a meter (m), 100 centimeters (cm) in a meter and 1000 meters in a kilometer (km). Length can be measured using a meter stick, metric ruler, or tape.

Volume is the space an object takes up. The standard unit for volume is the liter (L) and the most commonly used units for volume include the milliliter (mL), microliter (μL) and liter. For example, there are 1000 milliliters in a liter and 1000 microliters in a milliliter. The most common laboratory equipment used to measure volume is a graduated cylinder, beaker, flask or graduated pipet. Note: The curved surface of the water in a graduated cylinder is called the meniscus. The bottom of the meniscus is the point at which the volume of the water should be read (see Figure 1). Mass is the amount of matter in an object. The standard unit for mass is the gram (g) and the most commonly used units for mass include the microgram (μg), milligram (mg), gram (g) and kilogram (kg). For example, there are 1000 micrograms in a milligram, 1000 milligrams in a gram and 1000 grams in a kilogram. The most common piece of laboratory equipment used to measure mass is a balance.

Density is the amount of mass an object contains compared to its volume. Density is equal to mass divided by volume or D = m/v. When calculating density, mass should be in grams and volume in cubic centimeters (1 cm³ = 1 mL). Density is expressed in grams per cubic centimeter (g/cm³).

Temperature is the measure of how hot or cold an object is and is measured in units called degrees Celsius (°C) typically using a thermometer. Most thermometers contain either alcohol or mercury in a sealed glass tube. As temperature increases, the liquid expands in the tube at a uniform rate.

Contaminants in water are usually measured in parts per million (ppm), parts per billion (ppb) and parts per trillion (ppt). Although these particles are not seen, they can be measured in a laboratory to determine water quality. The comparison is in terms of grams of pollutant to grams of water. Since the density of water is 1 gram per milliliter, there are one million grams of water in 1000 liters. If there is one gram of pollutant in 1000 liters, or 1 milligram of pollutant in 1 liter, then the result is a pollutant in a concentration of 1 ppm.

Experiment Overview

In this laboratory investigation the student will conduct six separate laboratory activities in which length, mass, volume, density, temperature and concentration are quantitatively measured.

Materials

Prelab Questions

1. What instruments may be used to measure each of the following quantities?
   1. Length
   2. Mass
   3. Volume
   4. Temperature
2. What is density?
3. How might the concentration of a substance affect its ability to harm an organism?

Safety Precautions

Isopropyl alcohol is a moderate fire risk and slightly toxic by ingestion or inhalation. To avoid burns, use extreme caution while using heating equipment. Lamps and bulbs get very hot and can cause burns. Do not leave the lamps unattended. Wear chemical splash goggles. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

Activity 1. Measuring Length

1. Using a metric ruler, measure the length, width, and height of a textbook.
2. Record the measurements (in millimeters) on the Measurement in the Laboratory Worksheet.

Activity 2. Measuring Volume

Part A. Direct Method

1. Fill a test tube to the top with water.
2. Pour the water into a 100-mL graduated cylinder.
3. Record the volume of the water to the nearest milliliter on the worksheet.

Part B. Displacement Method

1. Fill the 100-mL graduated cylinder with water to the 50-mL mark.
2. Record the initial volume of water (in milliliters) on the worksheet.
3. Obtain a screw and carefully add the screw to the graduated cylinder. Note: To avoid cracking the graduated cylinder, tilt it slightly sideways then add the screw.
4. Record the final volume of water (in milliliters) on the worksheet.
5. Subtract the initial volume of water from the final volume of water and record the amount of water displaced (the volume of the screw in milliliters) on the worksheet.

Activity 3. Measuring Mass

1. Place a Styrofoam cup on the balance.
2. Record the mass of the Styrofoam cup (in grams) on the worksheet.
3. Measure 100 mL of water using a graduated cylinder.
4. Carefully pour all of the water from the graduated cylinder into the Styrofoam cup.
5. Record the mass of the water and cup on the worksheet.
6. Subtract the mass of the cup from the total mass and record the difference (mass of the water in grams) on the worksheet.

Activity 4. Determining Density

1. Record the mass of the Styrofoam cup (in grams) on the worksheet obtained in Activity 3, step 1.
2. Measure 30 mL of water using a 100-mL graduated cylinder.
3. Carefully pour the 30 mL of water into the Styrofoam cup.
4. Record the mass of the water and cup on the worksheet.
5. Subtract the mass of the cup from the total mass and record the difference (mass of the water in grams) on the worksheet.
6. Discard the water and dry the cup with paper towels.
7. Repeat steps 3 through 6 using 30 mL of salt water. Discard according to the teacher’s instructions.
8. Repeat steps 3 through 6 using 30 mL of isopropyl alcohol. Discard according to the teacher’s instructions.
9. Record all measurements on the worksheet.

Activity 5. Measuring Temperature

1. Use a ruler to measure from the bottom of a Styrofoam cup to a height of 3.5 cm.
2. Using a marker, draw a line on the Styrofoam cup at a height of 3.5 cm.
3. Repeat steps 1 and 2 with a second Styrofoam cup.
4. Fill one Styrofoam cup to the line with white sand. Note: This is approximately 125 g to 130 g. The sand should be level in the cup.
5. Fill the second cup to the line with black sand.
6. Place a thermometer in the center of each cup, halfway into the sand.
7. Record the initial temperature of the sand in each cup to the nearest 1.0 °C on the worksheet.
8. Place both cups under a heat lamp or in the sun, as directed by the teacher, so that they each receive an equal amount of light.
9. Using a stopwatch or clock, time the exposure for 8 minutes.
10. Record the temperature of each color of sand at 2-minute intervals during the 8-minute exposure on the worksheet.
11. Tip: Work on Post-Lab Question 8 during timing intervals.

Activity 6. Measuring Low Concentrations of Water Pollutants

1. Using a marker, label five medicine cups 1 through 5.
2. Using a graduated pipet, add 9 mL of water to each cup.
3. Using a graduated pipet, add 1 mL of red food dye to cup 1.
4. Stir well to mix the solution.
5. Record the percent concentration on the worksheet.
6. Flush the pipet with water.
7. Using the pipet, transfer 1 mL of solution from cup 1 to cup 2.
8. Repeat steps 4 through 7 for the remaining medicine cups, transferring 1 mL of solution to each successive cup and flushing the pipet with water each time.
9. Consult your instructor for appropriate disposal procedures.

Student Worksheet PDF

13553_Student1.pdf