Chemistry revision

John Newlands...
He arranged all the elements known at the time into a table in order of relative atomic mass. When he did this, he found a pattern among the early elements. The pattern showed that each element was similar to the element eight places ahead of it.
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Dmitri Mendeleev...
Mendeleev also arranged the elements known at the time in order of relative atomic mass. He realised that the physical and chemical properties of elements were related to their atomic mass in a 'periodic' way.
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Why did Mendeleev leave gaps?
endeleev thought it simply meant that the elements which belonged in the gaps had not yet been discovered.
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What does hard water contain?
dissolved compounds, usually calcium or magnesium compounds. For example, limestone contains calcium carbonate.
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Is it easier to for lather with soft water or hard water?
Soft water.
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How can you measure hardness?
By performing a titration with soap solution.
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Method of measuring hardness...
A known volume of water is put into a conical flask. Soap solution is added to it from a burette or pipette. The mixture is swirled to help it form lather. The volume of soap solution that needs to be added to form permanent lather is recorded.
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Types of hardness...
Temporary hard water can be softened by boiling it. Permanent hard water stays hard, even when it is boiled.
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2 Advantages of hard water...
Can improve the taste of the water and are good for the development and maintenance of bones and teeth.
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2 Disadvantages of hard water...
More soap is needed to produce lather, which increases costs. This happens with temporary or permanent hardness and the scum produced is unsightly spoiling the appearance of baths and shower screens.
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2 Ways of softening water...
Adding sodium carbonate to the water and using ion exchange columns.
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Other cards in this set

Card 2

Front

Dmitri Mendeleev...

Back

Mendeleev also arranged the elements known at the time in order of relative atomic mass. He realised that the physical and chemical properties of elements were related to their atomic mass in a 'periodic' way.

Card 3

Front

Why did Mendeleev leave gaps?

Back

Preview of the front of card 3

Card 4

Front

What does hard water contain?

Back

Preview of the front of card 4

Card 5

Front

Is it easier to for lather with soft water or hard water?

Back

Preview of the front of card 5
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