Module 1 Flashcards
- Define the terms matter, pure substances and mixtures
Define Matter
Matter is anything that has mass and occupies space.
What can matter be classified as?
It can be classified as pure
substance (element or compound) or mixture (homogenous or heterogenous).
What is a pure substance
sample of matter with both definite, constant composition and distinct
chemical properties.
What is a mixture?
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.
- Identify the differences between elements and compounds
Elements
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
Compounds
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.
- Apply the term ‘homogenous’ and ‘heterogenous’ to mixtures
What are the properties of a homogenous mixture?
- uniform composition;
- any sample of mixture is identical to any other sample.
- A solution is homogenous.
Examples of a homogenous mixture
homogonised milk, tap water, sea water, wine, vinegar
what are the properties of a heterogeneous mixture?
- composition that varies within mixture.
- Different components of
mixture can be seen.
Examples of a heterogeneous moixture
fruit cake, salad dressing, soda water, bread, sandy water, cereal in milk
What can happen when a substance is mixed with a solvent?
Can dissolve to form a liquid
but
Substance mixed with solvent does not always dissolve to form solution; it can form
suspension or colloid.
What is suspension?
heterogenous mixture and has distinguishable parts. It forms when
substance does not dissolve significantly.
Examples of suspension
muddy water, red blood cells in plasma
What is a colloid?
mixture of particles that consist of smaller clusters of ions or molecules. It is
evenly dispersed throughout solvent.
Example of colloid
Milk is colloid of fat in water.
mayonnaise, milk, butter, gelatin, and jelly
- Define the terms physical property and chemical property
Physical property
property describes features that can be observed or measured without changing the composition of matter; the element.
Examples of physical properties (10)
- melting point
- freezing point
- boiling point
- density
- physical state
- crystalline form
- colour
- conductivity (heat, electrical)
- hardness
- malleability
what is physical change?
is a change in a substance’s appearance without changing its chemical
composition.
how do you know if a physical change has occurred?
melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density
Chemical Property
property relate to how easily element undergoes chemical change. It can only
be observed during a chemical reaction; changing chemical composition of substance.
Examples of chemical properties
- acidity/basicity, flammability
- acid strength
- stability to heat
- activity (of a metal)
- electrode potential (ability to oxidise or reduce another substance)
Chemical change
is a process where one or more substances are changed into new
substances; involves rearrangement of atoms.
how do you know if a chemical change has occurred?
Color Change. Production of an odor. Change of Temperature. Evolution of a gas (formation of bubbles) Precipitate (formation of a solid)
- 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
Magnetic Separation
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
- Recovering aluminium cans from household waste
Filtration
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
- Removing solids from petrol
- Filtered water
- sand and water mixture
Evaporation
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
- clothes drying outside
- steam rising off of boiling pot of water
- obtaining salt from sea water
Distillation
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.
Fractional distillation
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
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)
Explain the difference between quantitative and qualitative analysis and give examples of each
Quantitative
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.
Qualitative
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
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)
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)
10 Recall the difference between physical and chemical properties
Physical property
Physical property is any characteristic that can be determined without changing
substance’s chemical identity.
Chemical Property
Chemical property is any characteristic that can be determined only by changing
substance’s molecular structure.
Physical Properties and Changes in State
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.
