Discovery 1-1 Matter

Discovery 1-1 Matter

A. Mass & Change

Scientists need some tools to describe matter in a quantitative way. Mass is a useful property of matter than we can measure to determine how much “stuff” we have. The balance is the tool used to measure the mass of an object. In this discovery, you will determine if the mass of a system changes when the appearance of the system changes.

· Follow the directions at each lab station.

· Record the initial and final mass of each system. Then, determine the change in mass. Record your mass change in the class data table. Finally, record the average mass change.

· Draw diagrams (at the smallest particle level) for each substance before and after each change.

· Explain why the mass changed or was unchanged for each activity.

Activity / Initial Mass
(g) / Final Mass (g) / Mass Change
(g) / Avg. Mass Change (g)
1. Pulling Apart Steel Wool
2. Burning Steel Wool
3. Melting Ice
4. Forming a Precipitate
5. Dissolving Sugar
6. Dissolving Alka-Seltzer

Pulling Apart Steel Wool Burning Steel Wool

Before After Before After

Melting Ice Forming a Precipitate

Ice Water Before After

Dissolving Sugar Dissolving Alka-Seltzer

Before After Before After

Conclusion: State the Law of Conservation of Mass in your own words.

Mass & Change Directions

1. Pulling Apart Steel Wool

1. Determine the mass of a compacted wad of steel wool in an evaporating dish.

2. Carefully pull apart the wad so that it occupies a volume roughly twice as great as before.

3. Determine the mass of the expanded wad of steel wool.

4. Roll the steel wool into a compacted wad to use for the next section.

2. Burning Steel Wool

1. Determine the mass of a compacted wad of steel wool in an evaporating dish.

2. Light a Bunsen burner. Hold the steel wool by tongs and heat it until it glows. Turn the steel wool in the flame so that all sides are exposed. [Tongs are hot—do NOT touch people or plastic!]

3. Determine the mass of burned steel wool and evaporating dish.

4. Place the burned steel wool in the labeled beaker.

3. Melting Ice

1. Measure the mass of a test tube, rubber stopper, and small piece of ice.

2. Warm the test tube in your hands to speed up the melting process. While waiting for the ice to melt, complete the “forming a precipitate” section.

3. When the ice is completely melted, measure the mass of the test tube, stopper, and melted ice.

4. Dump out the water from the test tube.

4. Forming a Precipitate

1. Fill a vial about 1/4 full of 0.1M Ca(NO3)2. Fill a vial about 1/4 full of 0.1 M Na2CO3. Stopper each vial and find the mass of both vials together.

2. Carefully pour the contents of one vial into the other.

3. Find the mass of both vials with stoppers after the reaction.

4. Pour the contents of the vial into the labeled beaker. Completely rinse each vial.

5. Dissolving Sugar

1. Fill a test tube about ½ full of water. Put a small amount of sugar on a piece of weigh paper. Find the combined mass of the test tube, water, stopper, and sugar/weigh paper.

2. Carefully pour the sugar into the test tube and stopper it. Gently swirl the test tube to get the sugar to dissolve. While doing this, do #6 below (Dissolving Alka-Seltzer).

3. Find the mass of the test tube, its contents, and the weigh paper.

4. Dump out the contents in the sink. Rinse the test tube.

6. Dissolving Alka-Seltzer

1. Fill a container (labeled AS container) about ½ full of water. Put about ¼ tablet of Alka-Seltzer on the lid of the container. Find the combined mass of the container, water, lid, and Alka-Seltzer.

2. Put the piece of Alka-Seltzer into the container and loosely place the lid on the container. Observe what happens as the Alka-Seltzer dissolves.

3. Find the mass of the container and its contents.

4. Dump out the contents in the sink. Rinse the container.

D 1-1 B. Classifying Matter

1. Pure Substances

Substance and
Formula / Density
(g/mL) / M.P.
(oC) / B.P.
(oC) / Appearance / Effect of
Magnet / Solubility
in Water / Others
sulfur, S / 2.07 / 115 / 445
iron filings, Fe / 7.87 / 1538 / 2862
salt, NaCl / 2.17 / 801 / 1413
sand, SiO2
sugar, C12H22O11 / 1.59 / 186
water, H2O / 1.00 / 0 / 100
ethanol, C2H5OH / 0.79 / -114 / 78

2. Mixtures

a. Iron-Sulfur Mixture

b. Sand-Salt Mixture

c. Water-Ethanol Mixture

The flask contains a mixture of ethanol and water. Describe and draw a diagram of what is happening in each part (flask, condenser tube, beaker) of the distillation process.

3. Mixtures, Compounds, & Elements

a. Iron-Sulfur Mixture vs. “Compounded” Iron Sulfide (video/demo)

b. Electrolysis of Water

· What is the formula for water? How do you know that?

· Observe the electrolysis of water. Describe what happens to the water.

· Describe the tests used to identify gases—hydrogen, oxygen, water.

· How do the volumes of the gases compare? (Ring of Truth, Episode 5 Atoms)

· Draw a diagram of the particles before and after electrolysis.

· What does this demonstration tell us about water? About elements and compounds? What is the meaning of the “definite composition of compounds?”

4. Particle Diagrams

Classify each particle diagram as a pure substance (element or compound) or mixture.