AQA A-Level Chemistry 7405
Atomic Structure
Amount of Substance
Bonding
Energetics and Thermodynamics
Kinetics
Chemical Equilibria
Redox and Electrochemistry
Acids and Bases
Periodicity and Group Chemistry
Period 3 Elements and Their Oxides
Transition Metals
Introduction to Organic Chemistry
Hydrocarbons
Halogenoalkanes, Alcohols and Organic Analysis
Carbonyls, Carboxylic Acids and Derivatives
Aromatic Chemistry and Amines
Polymers, Amino Acids, Proteins and DNA
Organic Synthesis, NMR and Chromatography
Amount of Substance
Acid-Base Titrations: Standard Solutions and Calculations
- 3 things to know
- Papers 1, 2 and 3
Overview
Making up a standard solution, and working concentration out from titre using moles = concentration × volume.
What you need to know
Answer each one before you reveal it.
A burette has an uncertainty of ±0.05 cm³ per reading. Calculate the percentage uncertainty in a titre of 25.00 cm³.
How do you convert volume in cm³ to volume in dm³?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is the formula relating moles, concentration and volume?
Model answer
n = c × V, where n is moles, c is concentration in mol dm⁻³, and V is volume in dm³
- 2
How do you convert volume in cm³ to volume in dm³?
Model answer
Divide the volume in cm³ by 1000
- 3
In a titration calculation, how do you determine the number of moles of the unknown substance?
Model answer
Use the moles of the known substance and the stoichiometric ratio from the balanced equation
- 4
What is meant by the titre in a titration?
Model answer
The volume of solution added from the burette to reach the end point
- 5
Why are rough titrations performed before recording accurate titres?
Model answer
To identify the approximate end point so that subsequent titrations can be performed more carefully near that volume
- 6
Why should concordant titres be used when calculating the mean titre?
Model answer
Because concordant results are consistent and reliable, reducing the effect of random errors
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