Chapter 3 & Chapter 4: Elements, Compounds and Mixtures, Solution and Suspensions and Separating Mixtures

Question 1

Define elements.

Answer 1

Elements are the basic building blocks of living and non-living matter. They cannot be broken down into simpler substances.

Question 2

Define compounds.

Answer 2

They consist of 2 or more elements that are chemically combined together.

Question 3

What are the characteristics of compounds?

Answer 3

They do not have the same properties as their constituent elements. The constituent elements of a compound are always chemically combined in a fixed proportion by mass. A compound cannot be separated into its constituent elements easily, it would need alot of energy to break it down.

Question 4

Define mixture.

Answer 4

A mixture consists of two or more elements and/or compounds that are not chemically combined together

Question 5

What are the characteristics of mixtures?

Answer 5

They have the same characteristics as their constituents. The constituents of a mixture can be separated easily and do not have a fixed proportion.

Question 6

What is a solution?

Answer 6

A solution is a mixture in which one substance dissolves completely in another substance.

Question 7

The substance that dissolves is called the ______

Answer 7

solute

Question 8

The substance in which the solute dissolves in is called the ______

Answer 8

solvent

Question 9

With a fixed volume of water, a solution with a low percentage of dissolved solute, it is known as a ___________. A solution with a high percentage of dissolved solute is known as ____________

Answer 9

dilute solution, concentrated solution

Question 10

What is rate of dissolving?

Answer 10

It refers to how quickly the solute dissolves in a solvent.

Question 11

What factors affect rate of dissolving?

Answer 11

Temperature of solvent, size of solute particles and rate of stirring.

Question 12

What is solubility?

Answer 12

It refers to how well a solute dissolves in a fixed volume of a particular solvent.

Question 13

What factors affect solubility?

Answer 13

Type of solute, type of solvent, temperature of solvent.

Question 14

Define suspension.

Answer 14

It is a mixture that contains insoluble substances in a solvent.

Question 15

What are the characteristics of a solution?

Answer 15

1. Particles of the solute cannot be seen
2. Solute does not settle to form solid deposits
   3.Light can pass through fully
3. Cannot separate via filtration.
4. Homogenous

Question 16

What are the characteristics of a suspension?

Answer 16

1. Insoluble substance can be seen
2. Insoluble substances can settle to form solid deposits
3. Light cannot pass through fully.
4. Can separate via filtration.
5. Heterogenous

Question 17

What are the 6 ways a mixture can be separated into its constituents by physical methods?

Answer 17

1. Magnetic attraction
2. Filtration
3. Evaporation
4. Distillation
5. Chromatography
6. Separating funnel

Question 18

What does magnetic attraction do?

Answer 18

It separates magnetic materials from non-magnetic materials

Question 19

What is the liquid that can pass through the filter paper?

Answer 19

Filtrate

Question 19

What is the solid that is left at the filter paper called?

Answer 19

Residue

Question 20

What does filtration do?

Answer 20

It separates substances of different particle sizes

Question 21

What does evaporation do?

Answer 21

It obtains a dissolved solid from a liquid

Question 22

What is crystalisation used for?

Answer 22

For substances which will decompose

Question 22

When can you use evaporation to dryness?

Answer 22

For substances which will not decompose

Question 23

What is distillation used for?

Answer 23

To separate substances with different boiling points through boiling and condensation.

Question 24

What is the liquid that distills over called?

Answer 24

Distillate

Question 25

What are boiling chips for?

Answer 25

To ensure smooth boiling

Question 26

Where should the thermometer be placed at?

Answer 26

At the mouth of the condenser to measure the boiling point of the liquid.

Question 27

How does chromatography work?

Answer 27

Based on the solubility of the substance in a solvent.

Question 28

Why must the starting line be drawn in pencil?

Answer 28

The pencil lead will not dissolve in the solvent and thus will not affect the results

Question 28

What are separating funnels used for?

Answer 28

To separate immiscible liquids of different densities.

Question 29

What is chromatography used for?

Answer 29

To separate small amounts of substances that dissolve to different extents in a particular solvent.

Question 30

Why must the starting line be above the solvent level?

Answer 30

To prevent the sample on the starting line from dissolving directly into the solvent.

Question 31

What are immiscible liquids?

Answer 31

Liquid that do not mix together

Question 32

What is reverse osmosis used for?

Answer 32

To purify water through a partially permeable membrane to separate ions, unwanted molecules and larger particles.

Question 32

What does a partially permeable membrane have?

Answer 32

Very small pores that only water to pass through.

Question 32

How can you determine whether a substance is pure or impure?

Answer 32

1. Measure its boiling point 2. Chromatography

Question 33

Are elements pure or impure?

Answer 33

Pure

Question 33

How can you tell if a substance is pure or impure when you use boiling or melting?

Answer 33

Pure: Substance melts/ boils at a fixed temp Impure: Substance melts/ boils over a range of temperature.

Question 34

Are mixtures pure or impure?

Answer 34

Impure

Question 35

Are compounds pure or impure?

Answer 35

Pure