Lab 2 Procedure

The five steps of the lab are:

  1. Measure the mass, volume, and length while creating a polymer.
  2. Calculate the density of a solid cube via geometric measurements and calculation of the solid’s volume.
  3. Calculate the density of an unknown metal solid via water displacement measurement and calculation of the solid’s volume.
  4. Calculate and compare the densities of a golf ball and salt water.

Safety for this lab:

  • Wear safety glasses at all times.
  • ALWAYS clean up your entire station and any spills made at shared stations.
  • DO NOT deposit broken glassware in trash, place into broken glassware container located near paper towels.

THE PROPER NUMBER IF SIGNIFICANT FIGURES WILL BE USED FOR ALL MEASUREMENT RECORDINGS AND ALL CALCULATION ANSWERS.

Part 1: Measure mass, volume, and length while creating a polymer.

l02_01 Using the analytical balance, zero out the balance with a l02_02small empty weigh tray.

Remove the empty weigh tray from the balance place a small scoop of solid calcium chloride into the tray. 

Place the tray back on the balance and measure it’s mass.  Record the mass correctly, example: 5.565 g (every digit shown on the analytical balance – including units). Using the iPad, take a picture of this measurement. Save this measured calcium chloride, you’ll be using it to make a solution soon.

l02_03l02_04Using a graduated cylinder, measure approximately 80 to 100 mL of
distilled water.
  Record the volume correctly, examples: 87.6 mL or 94.0 mL (record your number to the tenth place – including units). Using the iPad, take a picture of this measurement, try your best to show the meniscus.

l02_05Now, in a medium-sized beaker combine the measured water and calcium chloride and stir.

Locate the colored sodium alginate solutions on the center table in the lab room.l02_06 Obtain a full dropper amount and take back to your station.

When ready, attempt to squeeze the sodium alginate solution as a steady stream of liquid into the calcium chloride and water solution you made above.

l02_07Using your fingers pull out from the calcium chloride water solution, the polymer you have created. Using the iPad, record a short video of you pulling out this polymer from the solution.

Using a meter stick, measure the length of your polymer. Record the length correctly, example: 12.50 cm (record your number to the hundredth place  – including units)

Part 2: Calculate the density of a solid cube via GEOMETRIC MEASUREMENT and calculation of the solid’s volume.

l02_08 l02_09Measure the mass of a solid cube using the analytical balance. Record the mass correctly, example: 45.565 g (every digit shown on the analytical balance – including units). Using the iPad, take a photo of your cube.

l02_10Measure the length, width, and height of the solid cube using the caliper or centimeter ruler. Record the length correctly, example: 12.50 cm (record your number to the hundredth place  – including units).l02_11 Using the iPad, take a photo of one of these length measurements (try and get the ruler numbers clearly in the photo).

CALCULATE the volume and density of the solid cube; the equations are given below.  Record on your DATA SHEET.

Volume Equation for solid cube:  V = length x width x height, the units cm3

                    Density Equation: Density = mass divided by volume, the units g/cm

Part 3: Calculate the density of an unknown metal solid via WATER DISPLACEMENT MEASUREMENT and calculation of the solid’s volume. 

l02_12 l02_09Record the mass of a metal cylinder. Record the mass correctly, example: 45.565 g (every digit shown on the analytical balance – including units).

Fill a 100 mL graduated cylinder with approximately 50 mL of distilled water from the white spigot faucet at the lab sink or your bench top water bottle.  Look carefully at the volume and correctly record this INITIAL VOLUME on the DATA SHEET. Record the volume correctly, examples: 51.6 mL or 54.0 mL (record your number to the tenth place – including units).l02_14l02_13

Gently ease your metal cylinder (refer to picture) into the graduated cylinder noting the rise in the water level as the cylinder sinks to the bottom of the glassware.  Look carefully at the volume and record this FINAL VOLUME on the DATA SHEET. Record the volume correctly, examples: 57.6 mL or 59.0 mL (record your number to the tenth place – including units).

CALCULATE the volume and density of the metal cylinder; the equations are given to you on the Sample Data (and below).  Record on your DATA SHEET.

              Volume Equation for cylinder: V(final) – V(initial), the units mL

Density Equation: Density = mass divided by volume, the units g/mL

Part 4: Calculate and compare the densities of a golf ball and a salt water solution.

Golf Ball:

l02_15Record the mass of a golf ball using the analytical balance. Record the mass correctly, example: 45.565 g (every digit shown on the analytical balance – including units).

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.  Look carefully at the volume (large graduated cylinder has line increments of 5 mL) and record this INITIAL VOLUME on the DATA SHEET. Record the volume correctly, examples: 155 mL or 170. mL (record your number to the ones place value – including units)Using the iPad, take a picture of this measurement, showing the meniscus.

l02_17Gently ease your golf ball (refer to picture) into the graduated cylinder noting the rise in the water level as the golf ball sinks to the bottom of the glassware.  Look carefully at the volume (large graduated cylinder has line increments of 5 mL) and record this FINAL VOLUME on the DATA SHEET. Record the volume correctly, examples: 189 mL or 190. mL (record your number to the ones place value -including units)Using the iPad, take a picture of this measurement, showing the meniscus.

CALCULATE the volume and density of the golf ball; the equations are given to you on the Sample Data (and below).  Record on your DATA SHEET.

             Volume Equation for cylinder: V(final) – V(initial), the units mL

               Density Equation: Density = mass divided by volume, the units g/mL

Salt Solution:l02_18
Fill a 100 mL graduated cylinder with approximately 80 mL of NaCl supersaturated salt solution.
Record the volume correctly, examples: 87.3 or 84.0 mL (record your number to the tenth place – including units).

l02_09Now take an empty 150 mL beaker and record its mass using the analytical balance.  Record this INITIAL MASS on the DATA SHEET. Record the mass correctly, example: 98.462 g (every digit shown on the analytical balance – including units).

l02_19Carefully pour the salt solution from the graduated cylinder into into the measured 150 mL beaker. (A stirring rod can assist to prevent spillage, as shown.) 

l02_20Record the mass of the salt solution and 150 mL beaker using the analytical balance.  Record this FINAL MASS on the DATA SHEET. Record the mass correctly, example: 185.365 g (every digit shown on the analytical balance – including units).

 

CALCULATE the mass of the salt solution; the equation is given below. Record on your DATA SHEET.   Mass of salt = mass (final) – mass(initial), the units g

CALCULATE the density of the salt solution; the equation is given below. Record on your DATA SHEET.

                     Density Equation: Density = mass divided by volume, the units g/mL

l02_21Place the golf ball into the salt solution. When you’re done with the salt water do not discard in sink. Place back in bottle. Explain your observations based upon the density values of the golf ball and salt solution on the DATA SHEET.

Using the iPad, take a photo of the golf ball in the salt solution.

 

FINAL STEP: CLEAN YOUR STATION  

Use the sinks and soap to wash your glassware.  

PUT AWAY ALL EQUIPMENT AND CHEMICALS AND WIPE DOWN YOUR STATION.

Do not leave the lab until the instructor has inspected your clean station.