Lab: Sink or Swim - EPIC Chemistry



Lab 1: Sink or Swim? Defining Density

Engage: Why do you think the regular coke sinks and the diet coke floats?

Explore: The density of a substance is the mass of the substance divided by the volume it occupies. The formula is:

Density = Mass/Volume

1. What are the units for mass? ________

2. What are the units for volume? ________

3. Using the above mathematical formula, what are the units for density? ________

Materials:

- Water - Raisin

- Oil - Paper clips

- Corn syrup - White bean

- 10 mL graduated cylinder - Penny

- 2 x 100 ml beakers - Calculator

- 250 mL beaker

Procedures: Determine the densities of the 3 liquids using the following steps.

a. Collect 20 mL of corn syrup, oil, and water using your beakers.

b. Measure and record the mass of the 10 mL graduated cylinder

c. Measure out approximately 8 mL of corn syrup using the graduate cylinder. Record the exact amount measured

d. Measure and record the mass of the corn syrup and cylinder

e. Calculate the density of the corn syrup and record.

f. Pour corn syrup back into its beaker, thoroughly rinse out the graduated cylinder, and repeat steps b – f with the remaining liquids

Data Table

| |Corn Syrup |Oil |Water |

|Mass of 10mL graduate cylinder | grams | grams | grams |

|Mass of cylinder and substance | grams | grams | Grams |

|Calculate mass of substance | grams | grams | Grams |

|Volume of substance | milliliters | milliliters | milliliters |

| | | | |

| | | | |

| | | | |

|Show work to find density | | | |

| | | | |

| | | | |

| | | | |

| | | | |

|Density of substance |g/mL |g/mL |g/mL |

Now that you have the densities, list the substances from lowest density to highest density

Lowest _________________________ __________________________ __________________________ Highest

Explain:

If an object is ___________ dense than the liquid in which it is placed, it will ___________ on the liquid. If it is ___________ dense than the liquid, it will ___________.

You have the following terms to choose from to fill in the blanks once you finish the following activity.

Elaborate:

Now let’s try using different objects to see if they float or sink and estimate their densities. You will be indirectly determining the density of each object - a raisin, paperclip, bean and penny.

Procedures: Determine the densities of each of the 4 objects using the following steps:

a. Measure and record the mass of the first object

b. Measure approximately 8 ml of water into a clean 10 mL graduated cylinder. Record exact measurement.

c. Drop the object into the cylinder. Determine if the object floats or sinks

d. Record the new volume reading on the cylinder

e. Determine the density of the object using measured data.

f. Clean out the cylinder, return the object to its holder and repeat steps a – e with remaining objects

|Object |Mass of Object (g)|Float or Sink? |Initial volume of water |Final volume of water |Volume of the Object (mL) |Object density |

| | | |(mL) |(mL) |(final-initial volume) |(g/mL) |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

1. When the object floated, which was larger, the density of the object or the density of the liquid?

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2. When the object sank, which was larger, the density of the object or the density of the liquid?

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3. If you poured water, oil, and corn syrup into the same container, in what order, from top to bottom, will they appear separated?

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4. When determining the mass of the

Evaluate: DO NOT forget to write down UNITS!

DENSITY Practice

1. A box has a mass of 45 grams and a volume of 9 mL. What is the Density of the box?

D =

M =

V =

Will the object float or sink in water? EXPLAIN how you know. ____________________________________________ _____________________________________________________________________________________________________________________

2. In which of these units can density be expressed?

a. liters per gram ( L/g)

b. grams per milliliter (g/mL)

c. milliliters per cubic centimeter (mL/cm3)

d. cubic centimeters per milliliter (cm3/mL)

3. An object has a mass of 150 grams and a density of 3 g/mL. What is the volume of the object?

V =

4. An object has a density of 4 g/mL and a volume of 10 mL. What is the mass of the object?

M =

5. In order to calculate the density of an object we need to know the object’s _______________ and _____________

6. An object’s mass is 36 grams, its volume is 9 mL. What is the density of the object?

D =

M =

V =

Extend:

1. Using your experimental data, explain whether your predictions for which liquid was densest was correct or not. Be sure to refer to specific data, as well as compare to other liquids' results.

2. Using your experimental data, explain whether your predictions for which object was densest was correct or not. Be sure to refer to specific data, as well as compare to other objects' results.

3. When determining the densities of the three different liquids Why was it necessary to determine the mass of the volumetric flask prior to determining the mass of the measured out liquid?

4. If the mass of an object remains constant, but the volume increases, how is density affected?

5. If the volume of an object remains constant, but the mass increases, how is density affected?

6. Which is more dense, a 1 gallon trash bag filled with a pound of feathers, or a 1 gallon trash bag filled with a pound of bricks? Explain your reasoning below.

7. Which is more dense, 5 mL of 15 grams of sugar, or 2 mL of 4 grams of salt. Show your work/reasoning below.

8. Using what you know about density, write an explanation about why ice cubes float. (Hint: what happens when water freezes and forms ice?)

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More Float

Less Sink

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