MEASUREMENT AND DENSITY PROCEDURE INTRODUCTION: This experiment involves the measurement of mass and volume values followed by calculations of density. THE PROPER NUMBER IF SIGNIFICANT FIGURES WILL BE USED FOR ALL MEASUREMENT RECORDINGS AND ALL CALCULATION ANSWERS. The five parts to the experiment are: 1. Compare the measurements and recordings from three different laboratory equipment. 2. Determine the relative densities of solids and liquids via visual inspection of sample mixtures. 3. Calculate the density of an unknown metal solid via geometric measurements and calculation of the solid's volume. 4. Calculate the density of an unknown metal solid via water displacement measurement and calculation of the solid's volume. 5. Calculate and compare the densities of a golf ball and salt water. SUPPLY CHECKLIST: Before starting the laboratory exercise: 1. Obtain or locate the following equipment. Most can be found in the drawers and cabinet at your lab station or on center bench top in the laboratory:
100 mL and 500 mL graduated cylinders, stirring rod, 250 mL beaker, centimeter rulers, metal cylinder, golf ball, benchtop water bottle (with distilled water) 2. Locate the following substance. Most can be found on the center bench top or in the side fume hood in the laboratory:
four density demo samples, and sodium chloride (salt) solution
Use the white tap faucet for distilled water: EXAMPLE MEASUREMENT: Before you start to do any measurement: Look at the following example for length: Look at the graduated digits on the centimeter ruler. Identify the smallest digit (usually a decimal place value) that you would record a measurement (This is referred to as the proper digit based upon the precision of the instrument).
1 This measurement would be recorded as 12.20 cm. PROCEDURE: Part 1: Compare the measurements and recordings from 3 different laboratory equipment. 1. Using the analytical balance, measure the mass of ONE of the selected material (you select: a pencil, eraser, spatula, rubber stopper, water, etc.). Record the name of the item selected and its mass on the DATA SHEET.
IMPORTANT: Always record your number with the correct amount of digits based upon the precision of the analytical balance. Also include the proper units with your measurement. 2. Using the graduated cylinder, select any amount of water to measure volume. Record the name "water" and its volume on the DATA SHEET.
IMPORTANT: Always record your number with the correct amount of digits based upon the precision of the graduated cylinder. Also include the proper units with your measurement. 3. Using the centimeter ruler, measure the length of ONE of the selected material (you select: a pencil, eraser, spatula, rubber stopper, etc.). Record the name of the item selected and its length on the DATA SHEET.
IMPORTANT: Always record your number with the correct amount of digits based upon the precision of the centimeter ruler. Also include the proper units with your measurement. Part 2: Determine the relative densities of solids and liquids via visual inspection of sample mixtures. 1. View the four density demo samples - 2 samples will have 2 liquids in them and 2 samples will have 1 solid and 1 liquid in them. The contents of each sample are described on your data sheet. Note the color characteristics of each substance in the sample as indicated on the DATA SHEET.
2 2. Given the fact that less dense material float on material that is more dense and the fact that each substance in each sample has a different color, determine the most dense material in each sample. Record your findings of the DATA SHEET. Part 3: Calculate the density of an unknown metal solid via GEOMETRIC MEASUREMENT and calculation of the solid's volume. 1. Measure the mass of a metal cylinder using the analytical balance. Record its mass (with units) on the DATA SHEET.
2. Measure the diameter and length of the metal cylinder using the centimeter ruler. Record its length (with units) on the DATA SHEET.
3. CALCULATE the volume and density of the metal cylinder; the equations are given to you on the Sample Data (and below). Record the answers (with units) to your calculations on your DATA SHEET.
Volume Equation for cylinder: Density Equation: D = m/V Part 4: Calculate the density of an unknown metal solid via WATER DISPLACEMENT MEASUREMENT and calculation of the solid's volume. 1. Re-record the mass of your metal cylinder using the same analytical balance used in part 3. Record its mass (with units) on the DATA SHEET.
2. Fill a 100 mL graduated cylinder with approximately 50 mL of distilled water from the white spigot faucet at the lab sink or your benchtop water bottle. Record this INITIAL VOLUME (with units) on the DATA SHEET.
3 3. Gently ease your metal cylinder (refer to picture below) into the graduated cylinder noting the rise in the water level as the cylinder sinks to the bottom of the glassware. Record this FINAL VOLUME (with units) on the DATA SHEET.
4. CALCULATE the volume and density of the metal cylinder; the equations are given to you on the Sample Data (and below). Record the answers (with units) to your calculations on your DATA SHEET.
Volume Equation for cylinder: Density Equation: D = m/V Part 5: Calculate and compare the densities of a golf ball and a salt water solution. 1. Record the mass of a golf ball using the analytical balance. Record its MASS (with units) on the DATA SHEET.
2. Fill a 500 mL graduated cylinder with approximately 150 mL of distilled water from your benchtop water bottle or from the white spigot faucet at the lab sink. Record this INITIAL VOLUME (with units) on the DATA SHEET.
3. Gently ease your golf ball (refer to picture below) into the graduated cylinder noting the rise in the water level as the cylinder sinks to the bottom of the glassware. Record this FINAL VOLUME (with units) on the DATA SHEET.
4. CALCULATE the volume and density of the golf ball; the equations are given to you on the Sample Data (and below). Record the answers (with units) to your calculations on your DATA SHEET.
Volume Equation for golf ball: Density Equation: D = m/V 4 5. Record the mass of an empty 250 mL beaker using the analytical balance. Record this INITIAL MASS (with units) on the DATA SHEET.
6. Using a stirring rod (as shown below), carefully pour 150 mL of salt solution into the measured 250 mL beaker.
7. Record the mass of the salt solution and 250 mL beaker using the analytical balance. Record this INITIAL MASS (with units) on the DATA SHEET.
8. CALCULATE the mass of the salt solution; the equation is given below. Record the answers (with units) to your calculations on your DATA SHEET.
Mass Equation for cylinder: m = mfinal - minitial
9. Measure the volume of the of salt water (that you massed) with a 500 mL graduated cylinder. Record this VOLUME (with units) on the DATA SHEET.
10. CALCULATE the density of the salt solution; the equation is given below. Record the answers (with units) to your calculations on your DATA SHEET.
m D = Density Equation: V
5 10. Place the golf ball into the salt solution. Explain your observations based upon the density values of the golf ball and salt solution on the DATA SHEET.
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