Lesson 5: Properties of Matter II

Day 2

Activity 2: Independent Traits

Materials: calculator, candle wax (kit), heat source, large cups (kit), safety goggles (kit), saucepan, watch or timer
For today's activity, you will be using information from Day 1 of this lesson to figure out density. You will also be using new materials to investigate melting point, boiling point, and solubility. Use the "Independent Traits" activity pages to record your data.

Density

For density, you will use the weight and volume information you collected yesterday. (Although mass and weight are not technically the same, you will use the weight measurements for objects on Earth that you found yesterday.)

Density is a measure of the relationship between the mass of an object and its volume. Density is a simple calculation:
density = mass divided by volume (d = m/v)
Since density involves both mass and volume, its unit of measure is a little complex: grams per cubic centimeter (g/cm³). As you work on this activity, think about what patterns you see with regards to the increase or decrease of density.

Follow these steps:
  1. Find the mass (weight) measurements of your cube and three irregular objects from the Earth column of the table on the "Volume, Mass, and Weight" page from Day 1. Copy this information onto the "Density" table of the "Independent Traits" activity page.
  2. Copy the volume for each object onto the table. (For the cube, use the length x width x height calculation.)
  3. Calculate density by dividing each object's mass by its volume. Record your answers.
CAUTION: The following procedure involves the use of heat. Use caution and be sure to observe the following rules:
  • Wear safety goggles.
  • If you have long hair or hair that goes to the collar of your shirt, you should tie it back in a ponytail.
  • Do not stand over heat sources, regardless of how small.

Melting Point and Boiling Point

You will now compare melting points for water and for wax. Remember that the melting point is the temperature at which a substance changes from a solid to a liquid. You will also observe what occurs when water reaches its boiling point (the temperature at which a heated liquid turns to gas) and see whether the wax will reach its boiling point.

First, gather your materials: a saucepan, 2 cups of frozen water, 1 empty cup, candle wax, and a watch or timer. Next, follow these steps:
  1. Fill a saucepan with water, place the pan on the stove, and turn the burner's heat to low or medium. You want the water to become warm, similar in temperature to a hot bath. Do NOT boil the water.
  2. While waiting for the water to warm, remove one of the cups of ice from the freezer and place it and the block of wax next to each other. Do this away from the heat source on a table or countertop.
  3. Observe what happens to the wax and the ice after 5 minutes and make note of it on the "Melting Point" table. Make another observation 5 minutes later.
  4. After the 10 minutes, place the cup of frozen water aside and get the second cup out of the freezer.
  5. Place this cup of frozen water in the warm water bath. Do not let the warm water directly touch the ice.
  6. Place the wax in a similar cup and place that cup in the warm water bath as well. If the cup floats, weight the cup down.
  7. Make an initial observation, make a second observation at 5 minutes, and then a third at 10 minutes. Record your observations on the table.
  8. Remove the cups from the saucepan, put the pan of water back on the stove, and turn the burner temperature up so that the water begins to boil.
  9. Once the water boils, remove the wax from the cup and place it directly into the boiling water.
  10. Make an initial observation, a second at 5 minutes, and a third at 10 minutes. Be sure to note what is happening with both the wax and the boiling water. Record your observations on the table.
  11. Do NOT try to remove the wax from the boiling water. Turn the heat off and carefully remove the pan from the heat source. Allow the water and pan to cool completely before you remove the wax.

Solubility

Remember that solubility is the extent to which one substance is able to dissolve in another. Dissolve means to become absorbed. Consider the data you've collected in this activity and then answer the questions in the "Solubility" section of the activity sheet.
In this activity your child explored the concepts of density, melting point/boiling point, and solubility. This experiment requires parental supervision. NOTE: If you are having trouble removing the wax from the pan, try freezing the pan — the wax should then come off very easily.

Answer Key:
In both cases the ice will melt, and the rate of melting will vary based on the ambient temperature, with the warm water bath likely to speed up the rate that the ice melts. Since wax has a higher melting point than ice, the wax at room temperature should not change. It is possible that it may soften, but the general shape of the wax in the cup will not change. When the cup with wax is placed in the warm water, a change in shape is probable because the melting point of wax is between 125-140(degrees) Fahrenheit with pouring temperatures 10-30(degrees) Fahrenheit higher than the upper threshold depending on the wax. With regards to solubility, keep in mind that for an object or matter to be soluble it must be absorbed by the solvent, water in this case. Though wax may melt in warm water, it is not soluble because the water does not absorb it.

Q1: Yes. The water that was frozen was absorbed by the water that was being heated, so at some point you would not be able to tell the difference.
Q2: No. Based on the definition that solubility is the extent to which one substance is able to dissolve in another, one could argue that the water did not dissolve because it was the same substance. This is not solubility since only one substance was involved; it was a change in the state of matter (phase change).
Q3: The wax should have melted somewhere between 125(degrees) and 140(degrees) Fahrenheit (the time your child recorded will vary). Wax did not reach its boiling point because the melted wax did not change from a liquid to a gas.
Q4: No. Based on the definition of solubility, wax is not soluble in water.

Activity 3: Vocabulary Review

Materials: scissors
Cut out the squares found on the two "Vocabulary Review" pages and match them as follows:
  1. Match each term to its correct formula or picture.
  2. Match each term to its correct definition.
  3. Once you have confirmed that your choices are correct, gather the cards with the vocabulary words on them. Place on one side of the table the names of those properties that are independent of the amount of matter; place those that are dependent on the amount of matter on the other side of the table.
  4. After you have checked those answers, gather the vocabulary cards and find the two that have direct relationships, meaning if one increases, the other increases (and if one decreases, the other decreases as well).
Answer Key

#1 and #2
  • Density is a measure of the mass per unit volume of matter; its formula is D = m/v.
  • Melting point is the temperature at which a substance changes from a solid to a liquid; its corresponding picture is ice melting.
  • Boiling point is the temperature at which a heated liquid turns to gas; its corresponding picture is a pot of water boiling.
  • Solubility is the extent to which one substance is able to dissolve in another; its corresponding picture is sugar being stirred into water.
  • Volume is the size of a three-dimensional space enclosed within or occupied by an object; its formulas include length x width x height, 4/3 x (pi) x (radius)3, and (B x h)/3.
  • Mass is the property of an object that is a measure of the amount of matter it contains; its corresponding picture is a balance.
#3: Properties independent of the amount of matter — melting point, boiling point, solubility
Properties dependent upon the amount of matter — volume, mass, density

#4: Properties with direct relationships (if one increases, the other increases; if one decreases the other decreases)
This one is challenging. The assumption is that you are working with the same element consistently. Also, the assumption is that temperature remains constant. If mass increases, volume increases, and if mass decreases, volume decreases.