Properties of Matter — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A solution forms when one substance called the solute dissolves in another substance.
The solute is the substance that gets dissolved. For example, when you stir sugar into water, sugar is the solute because it breaks apart and spreads through the water.
2. The substance that does the dissolving in a solution is called the solvent.
The solvent is the substance that does the dissolving. Water is called the "universal solvent" because it can dissolve more substances than any other common liquid.
3. Stirring or heating a liquid can help a solute dissolve faster in a solvent.
Stirring moves fresh solvent past the solute, and heating gives particles more energy, so both actions speed up how quickly the solute dissolves.
4. A mixture of sand and water can be separated by pouring it through a filter to trap the sand.
A filter has tiny holes that let water pass through but trap the larger sand grains, physically separating the two parts of the mixture.
5. When no more solute can dissolve in a solvent, the solution is said to be saturated.
A saturated solution has absorbed the maximum amount of solute it can hold at that temperature, so any extra solute settles to the bottom undissolved.
6. Evaporation can be used to separate a dissolved solid from a liquid solution.
When the liquid evaporates, it turns into gas and leaves the dissolved solid behind. This is how sea salt is harvested from ocean water.
7. Oil and water do not mix because oil is insoluble in water.
Oil molecules are not attracted to water molecules, so the oil cannot dissolve and instead forms a separate layer on top of the water.
8. A heterogeneous mixture has parts that are not evenly spread out and can be seen.
In a heterogeneous mixture, the different parts are unevenly distributed and often visible to the eye, like a bowl of trail mix where you can see nuts, raisins, and cereal separately.
9. In saltwater, water is the solvent and salt is the solute.
Salt dissolves into the water, making salt the solute. The water does the dissolving, so it is the solvent in this solution.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Sand and gravel
→ Use a sieve — larger gravel pieces stay on top while sand falls through
Use a magnet — iron is attracted to magnets but sand is not
Saltwater
→ Use evaporation — water turns to vapor and leaves salt crystals behind
Use a sieve — larger gravel pieces stay on top while sand falls through
Iron filings and sand
→ Use a magnet — iron is attracted to magnets but sand is not
Use evaporation — water turns to vapor and leaves salt crystals behind
Food coloring in water
→ Homogeneous solution — dye particles spread evenly throughout the water
Homogeneous solution — dye particles spread evenly throughout the water
Correct matches: Sand and gravel → Use a sieve — larger gravel pieces stay on top while sand falls through; Saltwater → Use evaporation — water turns to vapor and leaves salt crystals behind; Iron filings and sand → Use a magnet — iron is attracted to magnets but sand is not; Food coloring in water → Homogeneous solution — dye particles spread evenly throughout the water.