2. List three commercial products that could
have been separated using sifting.
3. List at least three uses of filters to
separate components of mixtures.
4. Explain how a magnet could be used to
separate different types of metals at a
recycling centre.
Connect Your Understanding
5. Use the particle theory of matter to
explain why evaporation of seawater can
be used to obtain salt.
6. Use the particle theory of matter to
explain why air filters used in
automobiles and furnaces must be
changed regularly.
2. Flour, sugar, and sand.
3. Uses of filters include separating coffee grounds from coffee, separating solids from liquids in wastewater treatment, and removing particulate matter from air in HVAC systems.
4. A magnet could be used to separate ferromagnetic metals (such as iron and steel) from non-ferromagnetic metals (such as aluminum and copper) at a recycling center. By passing the mixed metals through a magnetic field, the ferromagnetic metals would be attracted to the magnet while the non-ferromagnetic metals would not be affected.
5. The particle theory of matter explains that all matter is made up of tiny particles (atoms, molecules, or ions) that are constantly moving and interacting with each other. When seawater is heated, the particles within it gain energy and move faster, causing some of them to break free from the liquid and enter the air as water vapor. Over time, as more and more water molecules evaporate, the salt concentration in the remaining liquid increases until it reaches the point where the salt can be isolated and collected.
6. The particle theory of matter explains that air contains tiny particles (such as dust, pollen, and other pollutants) that can accumulate on air filters over time. As more and more particles are trapped on the filter, it becomes clogged and less effective at removing unwanted substances from the air. Changing the filter regularly ensures that it can continue to function properly and maintain indoor air quality.