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30 Cards in this Set
- Front
- Back
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Volumetric analysis is what?
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A form of quantitative analysis involving the measurement of volumes of reacting solutions.
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What is titration?
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The process of measuring the volume of one solution needed to react with a measured volume of another solution.
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Redox titration?
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When one of the solutions contains a reducing agent and the other an oxidising agent.
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Mass concentration to percent weight per volume?
gL-1 to %w/v? |
Divide by 10
/10 |
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Mass concentration to parts per million?
gL-1 to mgL-1 |
x10^3
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parts per million to parts per billion?
mgL-1 to microgramsL-1 |
x10^3
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What is stochiometry?
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the relationship between the relative quantities of substances taking part in a reaction or forming a compound
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What is a limiting reactant?
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The reactant that is entirely consumed
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A reactant that is not entirely consumed?
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Excess reagent
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Three steps to Chemical titrations?
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1. Preparation of solutions to be used in the titration
2. Preparation of glassware to be used in titration 3. Performing the titration |
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What is a standard solution?
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A solution of accurately known concentration
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How is a standard solution prepared?
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By dissolving a known amount of solute in sufficient water to make an accurately known volume of solution, or it may be prepared by accurate dilution of a more concentrated standard solution, referred to as a stock solution.
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What is a standard solution prepared in?
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A volumetric flask.
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What is a primary standard?
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A standard solution that is prepared by dissolving a measured mass of solute in water to make known volume of solution.
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4 requirements to select a suitable primary standard
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1. Must react in some detectable way with the substance under analysis.
2. Be availble in pure form 3. Be stable in air and water (mustn't react with CO2, H2O or O2) 4. Must dissolve in water |
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What does AR stand for?
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Analytical reagent, and is the pure form of a primary standard.
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Rinsing: What is rinsed with solution and what not?
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A conical flask should no be rinsed with a solution, only diluted water. The rest are okay.
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How is the end point of a titration determined?
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The point at which the indicator shows the first permanent colour change in the conical flask is called the end point for the titration.
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How can a miniscus read better?
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using black card behind the burette.
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Indirect and back titration? Some info?
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They are carried out as a second step in an analytical procedure to determine the concentration of a substance in solution.
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What is a back titration?
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A form of titration in which an excess of standard reagent is added and then the reverse of the normal titration is carried out
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Common errors in titration
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Misreading a scale
Incorrectly transferring data to a table of reults Incorrectly carrying out a procedure |
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Systematic errors in titration
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Poorly calibrated electronic balance
Pipettes and burettes with chipped that are broken Parallax errors in reading levels of solutions Incorrect concentrations of solutions arsing from mistakes in rinsing glassware Manufacture mistake in calibration |
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Random errors in titration
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Uncertainty in determining the colour change to indicate the end point of a titration
Variable position of the eye when measuring the solutions in burettes |
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Minimising random errors?
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These can be minimized by repetition of the measurement and averaging results. Also by improving the skill of the experimenter by practice.
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Bromophenol Blue?
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Strong acid - Weak/Strong base
Yellow to blue |
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Phenolphthalein?
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Weak acid - Strong base
Colourless to pink |
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Starch?
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Iodine solution added to solution of a reducer
Colourless to blue |
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No indicator used?
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Permanganate solution added to a colourless solution of a reducer
Colourless to pink |
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What is a burette used for?
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Delivering know volumes of a liquid
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