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C31: Acids and Bases
Strength of Acids and Alkalis
The strength of an acid depends on the extent to which it ionises in water. A strong acid or alkali is
one which is 100% ionised in water. Hydrochloric acid, sulphuric acid and nitric acid are all strong
acids. Sodium hydroxide…

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6. Record the amount of acid you entered by reading the measurement on the burette

Be sure to repeat the entire process two or three times at least to ensure accuracy.

Calculations Involving Titrations
When talking about concentration, we tend to describe it as the amount of the solute (in…

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because it isn't very accurate ­ but we can use it to compare energy changes from different fuels.

When a reaction takes place, bonds are broken and new chemical bonds are made:

breaking bonds is an endothermic process,
because energy has to be taken in from the
surroundings to break…

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calculations to work out exactly how much energy has changed. There is one vital piece of information
we need to know to do this:

4.2 joules of energy raises 1g of water by 1°C

Hence the units involved in this energy change will be kJ/g/°C (kilojoules per gram per degree).…

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These two energy
level diagrams show HH bonds being made and broken. The left diagram shows an already bonded
HH bond being broken. This has a bond energy of +436kJ/mol, so we write H = +436kJ/mol on the
diagram next to the change in height arrow. The right side is…

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dissolve into a solvent at any given temperature, and b) predict how much solute will form again when
we cool down a hot solution.

The solubility curves for potassium nitrate, sodium nitrate and sodium
chloride are shown here. As you can see, the solubility of each one
increases with temperature…

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and forwarded to our homes. It is the dissolved substances which react with hard water to form scum.

In terms of economic factors, hard water is more expensive because more soap is required for the
same wash. The soap reacts with the magnesium and calcium ions in the water, forming…

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The problem with Newlands' table was that he was too determined to get it done and working that he
made some mistakes. What he didn't know was that there were still many elements to be found, so he
filled in octaves regardless of their properties, and some of them ended…

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Group 1 ­ Alkali Metals
We call the first group (Group 1) the alkali metals. These are lithium, sodium,
potassium, rubidium, caesium and francium. The first three of those elements being
reactive, you may experiment with their reactions in class, but the last three of those
elements are extremely reactive,…

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have coloured vapours. They are relatively typical nonmetals, in such that they are poor conductors of
heat and electricity, and that they have low melting and boiling points. At room temperature, fluorine is
a poisonous, yellow gas, whilst chlorine is a green poisonous gas. All of them are reactive.



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