States Of Matter And Mixtures

Question 1

What is the arrangement and movement of particles in solids, liquids and gases?

Answer 1

1. Solids: particles are tightly packed in a fixed structure and vibrate in place.
2. Liquids: particles are close but can slide past each other and move freely.
3. Gases: particles are far apart and move quickly in all directions.

Question 2

How do changes in temperature affect particle motion?

Answer 2

1. Increasing temperature gives particles more kinetic energy so they move faster.
2. Decreasing temperature reduces their energy so they move slower.

Question 3

What are the changes of state between solids, liquids and gases?

Answer 3

1. Solid to liquid = melting, liquid to gas = boiling/evaporating, gas to liquid = condensing.
2. Liquid to solid = freezing, solid to gas = sublimation, gas to solid = deposition.

Question 4

How are melting and boiling points used to distinguish between pure substances and mixtures?

Answer 4

1. Pure substances melt/boil at specific temperatures.
2. Mixtures melt/boil over a range of temperatures.

Question 5

How do impurities affect melting and boiling points?

Answer 5

1. Impurities lower melting points and raise boiling points.
2. The wider the range, the more impure the substance is.

Question 6

How do you choose an appropriate separation method based on properties of the substances?

Answer 6

1. Use filtration for solids in liquids, distillation for different boiling points.
2. Use chromatography for coloured mixtures and crystallisation for dissolved solids.

Question 7

What is filtration and when is it used?

Answer 7

1. Filtration separates an insoluble solid from a liquid using filter paper and funnel.
2. It’s used in purification like separating sand from salt water.

Question 8

What is crystallisation and when is it used?

Answer 8

1. Crystallisation separates a dissolved solid from a solution by evaporating the solvent.
2. It’s used to get pure crystals of a substance from a solution.

Question 9

What is simple distillation?

Answer 9

1. Simple distillation separates a liquid from a solution.
2. The liquid with the lowest boiling point evaporates first, condenses, and is collected.

Question 10

What is fractional distillation?

Answer 10

1. Fractional distillation separates a mixture of liquids with different boiling points.
2. Each substance evaporates at its own boiling point and is collected separately.

Question 11

What is chromatography?

Answer 11

1. Chromatography separates components of a mixture based on how they move through a medium.
2. Substances with higher solubility travel further up the paper.

Question 12

What does the Rf value represent and how is it calculated?

Answer 12

1. Rf value = distance travelled by substance ÷ distance travelled by solvent.
2. It helps identify substances based on how far they move in chromatography.

Question 13

How do you analyse the composition of inks using chromatography?

Answer 13

1. You place a spot of ink on chromatography paper and let solvent move through it.
2. Different components travel different distances, forming spots you can compare.

Question 14

What is the core practical for analysing the composition of inks?

Answer 14

1. Draw a baseline in pencil and place spots of different inks on it.
2. Dip into solvent, let it run, then measure and compare the distances of spots.

Question 15

What is the process of water treatment?

Answer 15

1. Water is filtered, sedimented, and chlorinated to remove dirt and bacteria.
2. Distillation can also be used for pure water, e.g. in labs or space missions.

Question 16

What are the phases of chromatography

Answer 16

Mobile phase- where the molecules can move. The mobile phase is always a liquid or a gas

Stationary phase- where the molecules can’t move. This can be a solid or a really thick liquid