Please enable JavaScript.
Coggle requires JavaScript to display documents.
CALCULATING THE CONCENTRATION OF AN ACID IN A HOUSEHOLD SUBSTANCE (What…
CALCULATING THE CONCENTRATION OF AN ACID IN A HOUSEHOLD SUBSTANCE
Which substances have acid?
Inorganic
Batteries (impractical for this practical)
Toilet cleaner
Vitamin C tablet
Organic
Food
Pineapples
Apples
Yogurt
Jelly
Drinks
Apple juice
Milk
Wine
Lemon juice
Cranberry sauce
Citric acid
Vinegar
What is an acid?
A substance that donates hydrogen ions.
When dissolved in with water, there are more hydrogen ions than hydroxide ions.
Has a neutralisation reaction with bases.
There are two different types of acids
Organic
Acids that can be found in nature (natural substances)
Inorganic
Substances that are manufactured in factories (made by humans)
What is a base?
A substance that accepts hydrogen ions.
When dissolved in water, there are more hydroxide ions than hydrogen ions.
Has a neutralisation reaction with acids.
Safety of these substances/acids?
As these are household substances containing the acid, they are all relatively safe when used responsibly.
What kind of acids can be found in household substances?
Acetic Acid: CH3COOH
Vinegar, tomato sauce.
Citric Acid: C6H8O7
Citrus, pineapple, fruits, jam, jelly, cranberry sauce.
Lactic Acid: C3H6O3
Milk, yogurt, dairy.
Ascorbic Acid: C6H8O6
Vitamin C - found in citrus and other fruits & also vitamin C tablets people would take.
Sulfuric Acid: H2SO4
Batteries and drain cleaners.
Malic Acid: C4H6O5
Apple juice
Tartaric Acid: C4H6O6
Wine
Hydrochloric Acid: HCl
Toilet cleaner
Which base will be most appropriate to use?
Since the reaction between acid + base is a "neutralisation", the best base for a specific acid needs the same amount of hydrogen the acid gives away.
Can be determined with equation.
Which indicator will be most suited?
Use an indicator with a pH in the pH range of the reaction
e.g average pH of vinegar is 3. Methyl yellow is good as its range is 2-9-4.
What actions can be taken and what calculations need to be made? (METHOD)
Titration
Acid-base titration
Determine bases specific composition
Determine acid and specific composition
Determine most suitable indicator
Complexometric titration
Redox titration
Determine suitable solution
4, Precipitation titration
n = m/Mr
C = n/v
Difference between acid-base and redox titration?
Acid-base
The substances involved are acids and bases
The substances take part in a neutralisation reaction forming water molecules
Weak acids and bases are used as indicators
More common as it can take place between any form of acid and base (weak and strong)
Redox
The substances involved are categorised as redox
The substances react through oxidation and reduction reactions
Some redox substances act as self indicators and for most cases, special redox indicators are used
Commonly seen among the 'd-block' elements
Evaporation
Create an aqueous solution using a soluble HYDRATED substance and water.
When a SAMPLE (record the volume) of this solution is evaporated to dryness and the solvent and the waters of hydration are driven off, a solid substance should remain.
We should be able to determine the original concentration of the solution from the original volume of solution and the weight of substance remaining after heating.
What is an acid base reaction?
A neutralisation reaction
A type of chemical process in which one or more hydrogen ions are exchanged between substances - allowing them to neutralise
Availability of these acids (how to get them from listed household substances)?
Tablets
Dissolve a single tablet in 200 mL of distilled water (in a volumetric flask if possible)
Fresh fruit (juice)
Juice the fruit and then strain the juice through cheesecloth to remove seeds and pulp which may block pipettes
Packaged fruit juice
This may also need to be strained through cheesecloth if it contains a lot of pulp or seeds
Thick liquids (sauces, etc.)
Dilute with distilled water till it is an acceptable consistency
Fruit (that cannot be juiced) and vegetables
Alternatively, the 100 g sample of fruit or vegetable may be blended in a food processor together with about 50 mL of distilled water; after blending, strain the pulp through cheesecloth - washing it with a few 10mL portions of distilled water (make the extracted solution up to 100 mL in a volumetric flask)
Cut a 100 g sample into small pieces and grind in a mortar and pestle; then add 10 mL portions of distilled water several times while grinding the sample - each time removing the liquid extract into a 100 mL volumetric flask; finally, strain the ground fruit/vegetable pulp through cheesecloth - rinsing the pulp with a few 10 mL portions of water and collecting all extract in the volumetric flask (make the extracted solution up to 100 mL with distilled water)