PURITY

​Review

Open Ended

Which sub-atomic particle has a positive electrical charge?

Open Ended

Which sub-atomic particle has the smallest mass?

Open Ended

Which sub-atomic particles make up the nucleus of an atom?

Open Ended

How are the individual atoms held together?

Open Ended

Explain how Thompson's model of the atom is different from one scientist use today?

Open Ended

Who discovered the electron? When did they discover it?

Open Ended

Who proved that the neutron existed? When the do this?

Open Ended

What two things did Rutherford discover about the structure of the atom?

Open Ended

How is Rutherford's model different fromnthe model scientists use today?

5.2 PURITY

​In this topic you will:
what is meant by purity.
calculate percentage purity.
describe how it is difficult to get a pure product.
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Open Ended

What does it mean if a substance id pure?

Open Ended

Which of these items are pure substances:

sodium chloride

oxygen

sea water

gold

orange juice

silver nitrate

copper oxide

soil

black ink

potassium

Open Ended

Which are the elements?

sodium chloride

oxygen

sea water

gold

orange juice

silver nitrate

copper oxide

soil

black ink

potassium

Open Ended

Which are mixtures?

sodium chloride

oxygen

sea water

gold

orange juice

silver nitrate

copper oxide

soil

black ink

potassium

Open Ended

Which are compounds?

sodium chloride

oxygen

sea water

gold

orange juice

silver nitrate

copper oxide

soil

black ink

potassium

PURE SUBSTANCE

Chemical purity refers to an element contains a single substance.
Pure substances are made from only one chemical element or one compound.
Pure substances have a sharp melting point and boiling point.
For example, salt is a pure substance made only of sodium chloride.

PURE ELEMENTS

Pure elements means that every one of its atoms is exactly the sam and made of just one type of atom.
for example, pure gold means made of only gold atoms. Pure silver means made of only silver atom.

Caratage’ is the measurement of purity of gold alloyed with other metals. 24 carat is pure gold with no other metals. Lower caratages contain less gold. For example 18 carat gold. It contains 75% gold and 25% other metals.

​925 silver contains 92.5 percent pure silver and is the standard for fine silver jewelry. For every 1,000 parts of metal, 925 of them are sterling silver, and the remaining 75 of them (7.5 percent) are an alloy.

​Diamonds are made from the element of carbon.
if they are pure, diamonds contain no other elements and colourless and translucent.
Diamonds will give other colour if they are mix with other elements. The colour is depend on the colour of the element that is mixed.

SEAWATER

Seawater is made up of water and various salts, such as sodium chloride. Sodium chloride can be obtained by evaporation.

​if you take 1000 g of seawater, about 35 gram (or 3.5%) of it is made up of salts. Of this 35 g, about 68% is sodium chloride; the rest is made up of other salts.

Salts are compound made from acid and alkali.  
The names tell you which acid and alkali has been used to form them.
For example, sodium chloride is formed from sodium hydroxide and hydrochloric acid

​PURE PRODUCTS

When scientists carry out a chemical reaction, it is important that they obtain a pure product.
Some simple reactions there is only one product.
In some other reactions, there may be more than one product.
When there is more than one product they are mixed up together. These products need to be separated and purified to produce whichever pure product you want.