Module 1

Question 1

1. Define the terms matter, pure substances and mixtures

Define Matter

Answer 1

Matter is anything that has mass and occupies space.

Question 2

What can matter be classified as?

Answer 2

It can be classified as pure

substance (element or compound) or mixture (homogenous or heterogenous).

Question 3

What is a pure substance

Answer 3

sample of matter with both definite, constant composition and distinct
chemical properties.

Question 4

What is a mixture?

Answer 4

are two or more pure substances physically combined together. It has variable composition and variable physical properties.

Physical properties of
mixtures can be changed, unlike compounds.

Question 5

2. Identify the differences between elements and compounds

Question 6

Elements

Answer 6

are composed of one type of atom.

Most non-metallic elements form discrete molecules with definite number of atoms.
Sulfur
forms a discrete molecule of 8 atoms.
Some non-metallic elements are monatomic (noble gases). Noble gases are generally
chemically inert.

Some non-metallic atoms form covalent networks or giant molecules.
Carbon forms
covalent networks of diamond and graphite, and giant molecule of graphene

Question 7

Compounds

Answer 7

Compounds contain two or more atoms of different elements chemically bonded together
in definite proportions.

Atoms in compounds can form molecules - a network of atoms. Molecule is group of two
or more atoms chemically bonded together.

Question 8

3. Apply the term ‘homogenous’ and ‘heterogenous’ to mixtures

Question 9

What are the properties of a homogenous mixture?

Answer 9

• uniform composition;
• any sample of mixture is identical to any other sample.
• A solution is homogenous.

Question 10

Examples of a homogenous mixture

Answer 10

homogonised milk, tap water, sea water, wine, vinegar

Question 11

what are the properties of a heterogeneous mixture?

Answer 11

• composition that varies within mixture.
• Different components of
  mixture can be seen.

Question 12

Examples of a heterogeneous moixture

Answer 12

fruit cake, salad dressing, soda water, bread, sandy water, cereal in milk

Question 13

What can happen when a substance is mixed with a solvent?

Answer 13

Can dissolve to form a liquid

but

Substance mixed with solvent does not always dissolve to form solution; it can form
suspension or colloid.

Question 14

What is suspension?

Answer 14

heterogenous mixture and has distinguishable parts. It forms when
substance does not dissolve significantly.

Question 15

Examples of suspension

Answer 15

muddy water, red blood cells in plasma

Question 16

What is a colloid?

Answer 16

mixture of particles that consist of smaller clusters of ions or molecules. It is
evenly dispersed throughout solvent.

Question 17

Example of colloid

Answer 17

Milk is colloid of fat in water.

mayonnaise, milk, butter, gelatin, and jelly

Question 18

4. Define the terms physical property and chemical property

Question 19

Physical property

Answer 19

property describes features that can be observed or measured without changing the composition of matter; the element.

Question 20

Examples of physical properties (10)

Answer 20

• melting point
• freezing point
• boiling point
• density
• physical state
• crystalline form
• colour
• conductivity (heat, electrical)
• hardness
• malleability

Question 21

what is physical change?

Answer 21

is a change in a substance’s appearance without changing its chemical
composition.

Question 22

how do you know if a physical change has occurred?

Answer 22

melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density

Question 23

Chemical Property

Answer 23

property relate to how easily element undergoes chemical change. It can only
be observed during a chemical reaction; changing chemical composition of substance.

Question 24

Examples of chemical properties

Answer 24

• acidity/basicity, flammability
• acid strength
• stability to heat
• activity (of a metal)
• electrode potential (ability to oxidise or reduce another substance)

Question 25

Chemical change

Answer 25

is a process where one or more substances are changed into new substances; involves rearrangement of atoms.

Question 26

how do you know if a chemical change has occurred?

Answer 26

``` Color Change. Production of an odor. Change of Temperature. Evolution of a gas (formation of bubbles) Precipitate (formation of a solid) ```

Question 27

5. Perform a series of first hand investigations to determine the physical properties that enable mixtures to be separated using the following separation techniques; magnetic separation, filtration, evaporation, distillation, fractional distillation

Question 28

Magnetic Separation

Answer 28

Passing mixture through a magnetic field to separate the magnetic and non-magnetic components property: existence of magnetic attraction Magnetic separation examples 1. separating iron fillings from sand 2. Recovering aluminium cans from household waste

Question 29

Filtration

Answer 29

process of separating undissolved solid is separated from a liquid of gad by passing the mixture through a filter Process - solubility of solid - difference in particle size examples of filtration 1. Removing solids from petrol 2. Filtered water 3. sand and water mixture

Question 30

Evaporation

Answer 30

separating a dissolved solid from a solution by vaporising liquid property: difference in boiling point presence of a solute Examples of evaporation 1. puddles disappearing 2. clothes drying outside 3. steam rising off of boiling pot of water 4. obtaining salt from sea water

Question 31

Distillation

Answer 31

A process that separates the liquid component of a mixture by boiling the solution and condensing the vapour back to a liquid property: diff in boiling points Distillation examples : purifying water, purification of alcohol, desalination, making liquefied gases from air.

Question 32

Fractional distillation

Answer 32

Process used to separate a mixture of several liquids based on their different boiling points Examples of fractional distillation: refining crude petroleum into usable products, perfume manufacturing, alcohol manufacturing

Question 33

6 Students design, plan and conduct first-hand investigations to separate: (going to skip cause its all prac, but if u wanna know how to do it refer to image.2 of chem syllabus/booklets)

Question 34

Explain the difference between quantitative and qualitative analysis and give examples of each

Question 35

Quantitative

Answer 35

Quantitative analysis identifies amount of element or compound present and is expressed in numerical value in appropriate units. eg. Mass, concentration or relative abundance of the components of a sample.

Question 36

Qualitative

Answer 36

Qualitative analysis identifies elements and compound present in a sample of unknown material, based on chemical/physical properties. e.g Colour of a sample or malleability of a metal

Question 37

8 Write the correct method to weigh 100mL of a solution of sand, salt and water in a 250mL beaker using an electronic balance (going to skip cause its all prac, but if u wanna know how to do it refer to image.2 of chem syllabus/booklets)

Question 38

9 Perform a first-hand investigation to determine the percentage composition of sand, salt, water mixture and ethanol & water using a given method (going to skip cause its all prac, but if u wanna know how to do it refer to image.3 of chem syllabus/booklets)

Question 39

10 Recall the difference between physical and chemical properties

Question 40

Physical property

Answer 40

Physical property is any characteristic that can be determined without changing substance's chemical identity.

Question 41

Chemical Property

Answer 41

Chemical property is any characteristic that can be determined only by changing substance's molecular structure.

Question 42

Physical Properties and Changes in State

Answer 42

Physical state is easiest to observe; most common physical states of matter are solid, liquid and gas Physical changes can occur within any state. May alter physical properties of substance, but not chemical nature. Reversible and occurs gradually within state of matter. Mixing; each component retains individual chemical properties and no new substance is formed Heating causes physical change; adding heat lead to substance expand in V + lower density, removing heat leads to reduction in V + increased density. With sufficient heat, substances may undergo phase transition; physical properties can change drastically in phase transition.