Please enable JavaScript.
Coggle requires JavaScript to display documents.
How can the acid concentration in everyday substances be determined? -…
How can the acid concentration in everyday substances be determined?
Everyday substances and what type of acids they contain
Citric acid
Orange juice
Lime juice
Lemon juice
Easier to source
Contains ascorbic acid and malic acid
Opacity of the lemon juice would render it difficult to determine a colour change
Carbonic acid
Soft drink
Difficult to use in calculations due to the presence of other acids, including phosphoric acid and citric acid, in soft drinks
Carbonic acid may evaporate throughout the titration
Sulphuric acid
Fertiliser
Difficult to source
Drain cleaners
If used, determine which brand to use, as not all drain cleaners contain sulphuric acid
Tartaric acid
Wine
10% of wine's acidity is contributed to by other acids
Lactic acid
Dairy products, such as milk and yogurt
Texture would be difficult to work with
Acid concentration
Unit of measurement
mol/L
g/mol
% by mass
Factors that affect acid concentration
Age of the acid
Intrinsic variability
Brand of the acid (i.e. drain cleaner)
Location grown (i.e. fruit and juice)
How
Titration
Calculation process
1) Calculate the concentration of the standard solution
2) Determine the number of moles of acid which react with the standard solution, using the required molar ratio
3) Calculate the concentration of the acid using the number of moles of acid and the volume of acid used
Prepare a standard solution
Determine the concentration of the base
Bases that could be used
Sodium hydroxide
Stronger tendencies to absorb moisture from the air (hygroscopic)
Sodium carbonate
Ensure it is anhydrous
Base high
Indicators that can be used
Methyl orange
Methyl red
Phenolphthalein
Strong base and strong acid
Weak acid and strong base
Variables and errors
Systematic
The presence of other acids
Potential measurement issues (i.e. scale)
Age of the standard solution - concentration changes as the base can react with the air while in storage
Would only affect the data if titration is occurring over the span of several lessons
Whether the solute has completely dissolved in the base, hence, changing the concentration and the amount of acid required to fully consume the base
Random
Intrinsic variability
Accuracy of titre readings
Uncertainty
Weaknesses in methodology
Contamination of substances within the glassware due to cleaning
Can be reduced through the correct rinsing of equipment
Controlled variables
The amount of indicator added
The volume of lemon used
Concentration of the primary standard solution
Uncontrolled variables
Temperature