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Kelso High School
Science
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Names and Formulae
Acids and pH
The word ACID means sour. We often say that a sour liquid tastes acid. Examples of
sour liquids that you will find in the home are vinegar, lemon juice, grapefruit juice
and sour milk.
You can find out if a substance is an acid or and alkali by dissolving it in water and
adding an indicator. An indicator is a chemical which changes colour in different pH
environments so by matching the colour of the solution to the colour chart, the pH of
the substance can be found. The two most commonly used indicators are universal
indicator and pH paper, which is like blotting paper with the indicator soaked into it.
When acid is neutralised by an alkali, a salt if formed. Common salt, or sodium
chloride is formed when hydrochloric acid and sodium hydroxide react together:
Hydrochloric acid + Sodium hydroxide  Sodium chloride + water
HCl
NaOH
NaCl
H20
The sodium (Na) part of the salt comes from the sodium hydroxide and the chloride
(Cl) comes from the acid
The tables below give the names of salts produce by some common acids and alkalis
Acid
Hydrochloric
acid
Nitric acid
Salt
….. Chloride
Sulphuric acid
….. Sulphate
….. nitrate
Alkali
Sodium
hydroxide
Potassium
hydroxide
Calcium
hydroxide
Salt
Sodium….
Potassium….
Calcium….
Rocks
Human beings have used rocks for many purposes. Examples include:
 Weapons
 Building (houses and roads, etc)
 Sculpture
 Burning
Rocks can be sorted into 3 types:
Igneous
Igneous rocks are those that have formed when magma, (hot, liquid rock) cools
and hardens. They are very hard and do not scratch easily.
Examples include granite, basalt and obsidian.
Sedimentary
Sedimentary rocks are formed when substances like sediment and silt get
carried in rivers and then are deposited where the river ends. When this
happens over millions of years more and more layers of sediment build up and
the grains at the bottom of the pile become squashed together. They can
scratch easily.
Examples include sandstone, limestone and chalk.
Metamorphic
This name means changed form. Sometimes existing rocks can be altered by
either heat or pressure. For example mountains are formed when layer upon
layer of rocks are piled on top of each other. This creates huge pressure and
this pressure can change the rock. Metamorphic rocks are usually very hard and
cannot usually be scratched easily.
Examples include marble and slate.
Revision Questions
1. Give 3 examples of uses of rock by humans.
2. Use lines to correctly match the following rock type, description and
examples:
3.
Rock Type
Description
Example
Sedimentary
Existing rocks altered by
Granite
pressure or heat
Metamorphic
Formed from cooled and
hardened magma
Igneous
Grains of silt pile up at
the end of a river and
get squashed to form
layers
Chalk
Marble
Revision Questions – Answers
1.
eg, building houses/roads/walls, statues, gravestones, burning coal, etc.
You may have given other correct examples.
2.
Rock Type
Sedimentary
Description
Existing rocks altered
by pressure or heat
Metamorphic
Formed from cooled and
hardened magma
Igneous
Grains of silt pile up at
the end of a river and
get squashed to form
layers
Example
Granite
Chalk
Marble
Soil
Soil is made up of a mixture of inorganic particles, organic matter (humus),
water and air.
The inorganic part of the soil includes sand, silt and clay.
Sand particles are the largest and have sharp edges and feel gritty. Soils with
lots of sand in them can hold lots of air but not much water.
Silt particles feel smooth and powdery. Soils with lots of silt feel smooth but
not sticky when they are wet.
Clay particles are the smallest. Soils with lots of clay hold lots of water but not
much air.
The organic part of the soil is known as humus. It is made up of decaying plant
and animal matter which add nutrients to the soil.
Soils have different characteristics and uses depending on the mixture of sand,
silt, clay and humus.
Revision Questions
1. List the four parts that make up soil.
2. i) Describe what is in the inorganic part of the soil.
ii) List the inorganic particles of soil in order of size starting with the
largest.
iii) Describe what humus is made of.
3. i) Suggest why a soil with a lot of sand is not good for growing crops.
ii) Suggest why a soil with a lot of clay is not good for growing crops.
iii) Suggest why a soil with very little humus is not good for growing crops
Revision Questions – Answers
1. Inorganic particles, organic matter (humus), water and air.
2.i) A mixture of sand, silt and clay.
ii) Sand, silt, clay.
iii) Dead, decaying plant and animal remains.
3.i) It cannot hold enough water for the crop to grow.
ii) It cannot hold enough air for the crop to grow.
iii) It does not contain enough nutrients for the crop to grow.
Minerals and metals
The rocks of the earth’s crust contain metal ores from which we get
all the metal we use. Metal ores are usually well mixed into rocks, but
sometimes they are found pure. A pure metal ore is called a mineral.
Testing for metals
When a geologist is searching for metal ores he can do a quick, simple
test called a flame test to identify the metal present. The ore is first
ground to a powder and then dissolved in acid to release the metal. The
ore and acid are then heated on a wire in a Bunsen flame and the colour of
the flame identifies the metal.
Element
Flame colour
Barium
Green
Calcium
Orange –red
Copper
Blue-green
Lithium
Red
Potassium
Lilac
Sodium
Yellow
Recognising a chemical reaction
All chemical reactions produce new substances. These can be
recognised by




A colour change
An energy change (the temperature increases)
Effervescence (fizzing – the production of a gas)
Precipitation (the making of a solid from liquids)
Corrosion and rusting
CORROSION is the changing of the surface of a metal into a
compound.
RUSTING
is the special name given to the corrosion of iron.
Rusting can only happen if OXYGEN and WATER can both get to the
iron together. As air contains both oxygen and water, any iron object will
rust if left outside unprotected. The brown solid which forms is a
compound of iron, oxygen and water. The layer of rust is very weak and
falls off the surface of the iron very readily. The iron underneath then
starts to rust, until eventually the whole piece of metal corrodes.
Prevention of rusting
There are 4 main methods of preventing rusting




Barrier methods – stopping the oxygen and water reacting the
iron
Cathodic – using the negative terminal of a battery
Plating – coating the iron with another metal
Sacrificial – another metal been forced to corrode whilst it
protects the iron