C7: Volumetric Analysis
Terms in this set (11)
Stages of a quantitative analysis
1.Accurately measure out a specific mass or volume of the sample.
2.If the sample is a solid, dissolve it in a known volume of water.
3.Measure a property of solution quantitatively (by reacting unknown acid with an alkali of known concentration until solution is neutral)
4.Analyse results to calculate required measurement of unknown substance (concentration of unknown acid).
5.Repeat measurement using another sample to check results are consistent/reliable.
6.Estimate the degree of uncertainty in the results.
What is a standard solution?
One that's been made by dissolving an accurate mass of reactant into a known volume of water. Means that concentration of standard solution is accurate.
What is the concentration of a solution and what is it measured in?
The number of grams of solute in a litre of the solution. Measured in g/dm^3
What does 1dm^3 equal?
What does an Acid-Base titration do?
Measures how much of an acid is needed to neutralise a base.
Stages of an Acid-base titration
1.Add a few drops of indicator to conical flask.
2.Fill a burette with with standard solution. Run solution through burette to fill jet at bottom. Record reading on burette.
3.Slowly add solution from burette to conical flask. Swirl flask to mix solutions.
4.When solution about to change colour, add solution drop by drop.
5.When solution changes colour, record reading on burette.
What does accuracy describe?
How close a result is to the true value.
What is precision a measure of?
The spread of the measured values. If there is a big spread, the uncertainty is large.
What is the calculation for percentage error?
Uncertainty/Average X 100
What is the formula for the concentration of a solution?
Concentration= (mass X 1000)/Volume
What is the formula for the mass of solute dissolved in a solution?
Mass= (Concentration X Volume)/1000