A mixture contains two or more substances that are combined physically, not chemically, so they can be separated again. Filtration uses a barrier to catch an insoluble solid while liquid passes through. Evaporation removes a dissolved solid by boiling off the liquid it's dissolved in. Distillation separates two liquids with different boiling points by boiling off and collecting one of them.
Example
To get salt back from salt water, you'd use evaporation — boil off the water and the salt crystals are left behind. To separate sand from water, you'd use filtration instead, since sand doesn't dissolve.
Key terms
Filtration:
Separates an insoluble solid from a liquid using a barrier.
Evaporation:
Removes a dissolved solid by boiling off the liquid.
Distillation:
Separates liquids using differences in boiling point.
Soluble:
Able to dissolve in a liquid.
Questions
1. Mixing salt into water creates a:
Compound
Mixture
Element
Nothing new
2. Which of these is a mixture?
Pure water
Salt and pepper mixed in a bowl
A single grain of salt
Oxygen gas
3. A colander (strainer) used to drain pasta water is an example of:
Evaporation
Filtration
Distillation
None of these
4. If you leave a puddle of salty water in the sun, the water evaporates and leaves behind:
Nothing
Salt
More water
Air
5. Sand and water can be separated because sand:
Dissolves in water
Does not dissolve in water
Turns into gas
Becomes salt
6. A mixture contains:
Only one substance
Two or more substances not chemically joined
Nothing at all
Only gases
7. Which method would you use to separate rice from water after cooking?
Filtration (draining)
Distillation
Magnetism
Evaporation only
8. Filtration separates:
Two liquids
An insoluble solid from a liquid
Two gases
A solution into ions
9. Evaporation is used to separate:
A dissolved solid from a liquid
Two solids
Two gases
An insoluble solid from a liquid
10. Distillation separates liquids based on differences in:
Colour
Boiling point
Weight
Smell
11. A mixture's parts, unlike a compound's, can be:
Chemically bonded only
Physically separated
Never separated
Only seen with a microscope
12. To get clean drinking water from seawater, you would use:
Filtration
Distillation
A magnet
Nothing needed
13. Separating sugar dissolved in water back into solid sugar uses:
Filtration
Evaporation
A magnet
Freezing only
14. Which everyday item works like a filter?
A magnet
A tea strainer
A thermometer
A torch
15. You have a mixture of sand, salt and water. What is the best first step to separate all three?
Filter out the sand first, then evaporate the water to get the salt
Evaporate everything at once
Use a magnet
Add more water
16. Why can't you use filtration to separate salt from water?
Salt dissolves and passes through the filter with the water
Salt is magnetic
Water evaporates too fast
Filters don't exist for liquids
17. A chemist wants to separate two liquids with different boiling points, like water and alcohol. The best method is:
Filtration
Distillation
Using a magnet
Freezing only
18. Which statement correctly compares a mixture and a compound?
A mixture's parts can be physically separated; a compound's parts are chemically bonded
A compound's parts can be physically separated; a mixture's cannot
They are exactly the same
Neither can ever be separated
19. If you evaporate a cup of seawater completely, what is left in the cup?
Nothing
Salt (and other dissolved minerals)
Pure water
Sand
20. Which separation method would work best to remove iron filings mixed into sand?
Filtration
A magnet
Distillation
Evaporation
21. Distillation is best suited to separating:
Two solids
Two liquids with different boiling points
A magnetic solid from a mixture
Two identical liquids
Answer key (parent copy)
1. Mixture
2. Salt and pepper mixed in a bowl
3. Filtration
4. Salt
5. Does not dissolve in water
6. Two or more substances not chemically joined
7. Filtration (draining)
8. An insoluble solid from a liquid
9. A dissolved solid from a liquid
10. Boiling point
11. Physically separated
12. Distillation
13. Evaporation
14. A tea strainer
15. Filter out the sand first, then evaporate the water to get the salt
16. Salt dissolves and passes through the filter with the water
17. Distillation
18. A mixture's parts can be physically separated; a compound's parts are chemically bonded