Who's cheating on the vinegar?

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Who's cheating on the vinegar?

Problem

        Lots of people like to put vinegar on chips. But are we getting our

money's worth. The manufacturers could be watering it down to make it

less concentrated.

        We want to find out who is cheating on the vinegar. We have been

given four samples from different shops to test which is

a) most concentrated

b) best value for money.

Scientific Knowledge

        An acid is a substance with a pH below 7. Some example of acids

are, Milk of Magnesia, vinegar and lemon juice. Acids include ascorbic

acid, citric acid, hydrochloric acid and ethanoic acid which we will be

using in this experiment. It is a weak acid with a pH of 3.

        Alkalis have a pH of 8 or above. We will be using Sodium hydroxide

which is a strong alkali of 14.

        An indicator is something which is one colour in an acid and

another in an alkali. This means you use it to show what pH value a

soultion is. Common indicators are, litmus and methyl orange but we will

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be using Phenolphthaleins. This is colourless in an acid  but it goes bright

pink in an alkali. This means that the solution will turn pink when it turns

from an acid to an alkali.

        The term concentrated means to have more of the main

substance and less water.

        When we mix an acid and alkali, we get a salt and water. It will be

like the following equation:

ethanoic     +    sodium   ->   sodium  +  water

acid                hydroxide      ethanate

Plan

Independent ...

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