Mixtures 7 Science Term 1

What is a mixture?

• When a solute dissolves in a solvent

• A very concentrated solution

• Something made from two or more substances mixed together

• Two or more substances chemically bonded to each other

When a substance dissolves in water, why can you no longer see it?

• The water molecules are more numerous than the particles of the substance

• The particles of that substance are no longer present in the water

• The particles of that substance spread out so thinly that they are no longer visible

• The particles of that substance react with the water particles to become different chemicals

When sugar dissolves in water, which is the solute?

• There is no solute

• Sugar

• Water

• Sugar water

Is carbonated water (fizzy drinks) an example of a solution, and why?

• Yes, because carbon dioxide gas is dissolved in water.

• Yes, because carbon dioxide forms a colloid with water

• No, because you cannot dissolve carbon dioxide gas in water

• No, because solutions can only have liquids

What is the main sign that a mixture is a solution?

• It has water as a solvent

• It is transparent (you can see through it)

• It is colourless

• The sediments eventually settle to the bottom with enough time

What is a saturated solution?

• A solution that does not contain any solute

• A solution that cannot further dissolve any solute

• A very concentrated solution

• A very dilute solution

What is the main difference between a suspension and a colloid?

• If you shine a beam of light through a suspension, you can see the beam, but you cannot in a colloid

• A colloid is a more concentrated version of a suspension

• If you let both mixtures stand for a long time, a suspension will eventually separate on its own.

• Only colloids can be re-mixed once it has been separated into its components

Which is the correct order of mixtures from most finely spread out to least finely spread out?

• Solution, colloid, suspension

• Colloid, suspension, solution

• Suspension, colloid, solution

• Solution, suspension, colloid

How does decanting work?

• Magnets are used to separate some metals from others (ones that can be attracted by magnets)

• Heavier particles in the mixture sink by gravity and the top layer is poured off

• Particles are given an electric charge and passed through electrically charged plates

• A barrier is used with holes that allows smaller particles to get through but not larger ones

How does sieving work?

• A barrier is used with holes that allows smaller particles to get through but not larger ones

• Heavier particles in the mixture sink by gravity and the top layer is poured off

• Particles are given an electric charge and passed through electrically charged plates

• Magnets are used to separate some metals from others (ones that can be attracted by magnets)