Physics: Sodium Hydroxide and Commercial Vinegar Essay

Titration of Vinegar
Problem: To find out if the strength of a product is the same as what a company claims it to be,
E.g. ethanoic acid in vinegar, or alcohol in wine.

Select a Problem:
I chose to figure out if the product Idun vinegar contains 7% ethanoic acid which is what they claim it to be. There are a number of ways to do so; this includes combining the vinegar with an alkali of known concentration, with an indicator to show when it has been neutralised, from this data you can calculate how many moles of ethanoic acid there are according to how much alkali was required to achieve it, this is called a titration. Another method would be to combine the vinegar with a metal
(magnesium) which is known to create a salt and hydrogen when combined. What this means is we can measure the amount of hydrogen, salt, or metal required to finish the reaction, and then find the number of moles of ethanoic acid in Idun vinegar. For these calculations to work the concentration (amount of moles) of one of the reactants or products must be known. I decided to use the method called a titration to find out if the commercial vinegar is 7% ethanoic acid, as they claim it to be.

Hypothesis:
Combining an alkali of a known concentration to an acid can be used to determine the amount of moles of ethanoic acid in the commercial vinegar. This is because an alkali can neutralise an acid, what this means is that if we know how much of an alkali there is in a solution and we know how much of it used to completely neutralise the acid we can calculate how many moles of ethanoic acid there are in the commercial vinegar.

Introduction:
What is a titration?
A titration is a method of finding out an unknown concentration of a known reactant. A titration is when you combine an acid and an alkali (often they are strong acids and alkalis). You use it to figure out how many moles you have in an acid or alkali, you need to know how many moles there are in the other for this to be of any use. You add the acid into the alkali using the burette until the pH is 7 this is when the titration normally ends if you are using acids and alkalis of equal strength. The endpoint of the titration is reached when there is an equal concentration of the titrant and the solution of unknown concentration.
How is this titration different?
The difference between a conventional titration and the titration I did is that I dropped the alkali into the acid as opposed to dropping the acid into the alkali. I did this to prevent any unwanted harm to my mouth which would occur had I sucked up the sodium hydroxide with the pipettes instead of the vinegar.

Apparatus:
Burette, pipette, conical flask, beakers, retort stand, wash bottles, volumetric flask

Method:
I started by making diluted vinegar which I did by adding 2 pipettes full (1 pipette is 10ml) of the commercial vinegar into a 250 ml flask. I then filled the rest with water up to the 200 ml mark, this means I used a 1:9 ratio to dilute the vinegar this means the dilute vinegar is 10% of the original concentrated solution which is in perfect proportion to the 0.1 molar solution of sodium hydroxide we used. I diluted the vinegar to conserve the NaOH (sodium hydroxide). To make the 0.1 molar solution of sodium hydroxide I had to find 1 mole of sodium hydroxide (NaOH). To do this I found the atomic mass of NaOH which is 23 for sodium, 16 for oxygen and 1 for hydrogen. 23+16+1=40, the sum of this is 40g which is the mass of a mole of sodium hydroxide. But since I wanted a 0.1 molar solution that means I had to divide 40g by 10, 40/10=4g, this results in 4g in 1 litre of water for a 0.1 molar solution. However I only needed to make 500ml of NaOH meaning it must be divide by 2,
4/2=2, this results in 2g of sodium hydroxide into 500ml of solution. The event following shows us pouring the pre-made 0.1 molar solution of sodium hydroxide. This was created by mixing 2g of
NaOH base to

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Physics: Sodium Hydroxide and Commercial Vinegar Essay

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