Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chemistry Deconstruction: Determining the acid concentration of a common…
Chemistry Deconstruction: Determining the acid concentration of a common everyday substance
Acid
What is an acid
A substance with a pH lower than 7
Strong Acid - pH 0-3
Hydrochloric Acid
Sulfuric Acid
Weak Acid - pH 4-7
Acetic Acid
Hydrocyanic Acid
pH is the measure of the amount of hydrogen ions and hydroxyl ions within a substance
Reactions with Acids
Acid + Metals -> Salt + Hydrogen Gas
Acid + Base -> Salt + Water (Neutralisation Reaction)
Acid + Carbonate -> Salt + Water + Carbon Dioxide
Common everyday acids
Lemon / Orange Juice - Citric Acid
Drain Cleaner - Sulfuric Acid
Baking soda - Carbonic Acid
Phosphorus fertiliser - Phosphoric Acid
Dairy products (Milk, yoghurt) - Lactic Acid
Factors which affect acid concentration
How long the acid has been stored
Different brands of the same acid
Temperature
Measurement of acid concentration
mol/L
% w/v
g/mol
How to determine the concentration of an acid
Titration Stoichiometry
The titration process can be carried out to determine the unknown concentration of a solute with a known solute concentration
Can be calculated using C = n/V
C = Concentration (mol/L)
n = Number of moles
V = Volume in litres
The concentration of the standard solution is calculated
The number of moles of the acid required to react with the standard solution is calculated, with respect to the mole ratio
Calculate the concentration of the acid using moles (mol) of acid divided by volume (L) of acid
Apparatus
Volumetric pipette
Volumetric/Conical Flask
Burette
Retort stand
Burette Clamp
Indicator - Methyl Orange, Phenolphthalein, Methyl Red, Bromothymol Blue, et al.
Variable and Errors
Controlled Variables
Volume of Acid used
Amount of indicator added
Concentration of the standard solution
Uncontrolled Variable
Temperature
Random Errors
Leftover impurities in the glassware
Can be eliminated by thorough rinsing of equipment
Accuracy of titre readings
Uncertainty
Meniscus effect
Systematic Errors
Presence of other acids in the common everyday substance
The concentration of the standard solution may change as the base may react with air whilst in storage, hence could affect data if titration is completed over the course of several lessons