C5 Flashcards
What is purity?
- When a substance is referred to as pure it means nothing has been added to it
- If a substance isnt pure it is referred to as a mixture
What is chromotography?
- It is an analytical method used to seperate substances in a mixture
- Two phases- mobile and stationary
- Mobile phase-Where the particles of the phase are able to move
- Stationary phase-where the particles of the phase cant move
- You need to be able to work out the retention factor(rf)
- rf=Distance travelled by substance/Distance travelled bu solvent
IWhat is the paper chromotography practical?
- Filter paper, pencil, beaker, lid, solvent and substance you are testing
1. Draw a line close to the bottom of the filter paper with a pencil(insoluble)
2. Spot of substance to the line and place in a beaker with solvent, making sure the solvent doesnt touch the spot but is just below
3. Place a lid on top of the container to minimise the evaporation of the solvent
4. The solvent should be allowed to seep up the paper until it has nearly reached the top then mark the point at which the solvent reached with a pencil
5. The end result shows a chromatogram
How do you test for anions?
Halide ions
1)Chloride-acidify with dilute nitric acid then acid silver nitrate solution-white precipitate AgCl(s)
2)Bromide-acidify with dilute nitric acid then acid silver nitrate solution-cream precipitate AgBr(s)
3)Iodide-acidify with dilute nitric acid then acid silver nitrate solution-yellow precipitate AgI(s)
4)Sulfate-acidify with dilute nitric acid then acid silver nitrate solution-white precipitate BaSO4(s)
Flame test for metal ions
- Lithium-Crimson flame
- Sodium-yellow flame
- Potassium-lilac flame
- Calcium-red flame
- Copper- green flame
Test for positive ions(NaOH)
Calcium,Ca2+-white precipitate-Ca(OH)2(s)
Copper(//). Cu2+-Blue precipitate-Cu(OH)2(s)
Iron(//),Fe2+-green precipitate-Fe(OH)2(s)
Iron(///), Fe3+-brown precipitate-Fe(OH)3(s)
Zinc,Zn2+-White precipitate then disolves-Zn(OH)2(s)
How do you work out relative mass?
sum of (Isotope abundance x isotope mass number)
/sum of abundances of all the isotopes
What is the mole?
The name given to a specific number
6.022 × 10(to the power of 23)
Mass(m)=(M)Moles x molar mass(Mr)
moles(M)= concentration(Mol dm-3) x volume(dm-3)
What is percentage yield?
- The amount of product you get out of a reaction-the percentage yield refers to the amount in comparison to what you should realistically be getting
- Percentage yield =actual mass of products/maximum theoretical mass
What is percentage yield?
- The amount of product you get out of a reaction-the percentage yield refers to the amount in comparison to what you should realistically be getting
- Percentage yield =actual mass of products/maximum theoretical mass
What is concentration?
The amount of substance in a given volume of a solution
How do you use titration to measure concentrations?
1)Using a pippette filler, add a set volume of alkali to a conical flask with a few drops of indicator
2)use a funnel to fill a burette with a standard solution of an acid
3)Using the burrette, add the accid to the alkali a bit at a time while twirling the flask
4)When the indicator changes colour you know that the alkali has neutralised
5)record the final volume of acid in the burette , along with initial reading
What are the generic reactions of acids?
- acid +alkali=> salt +water
- Acid + base =>salt + water
- Acid + metal => salt + hydrogen
- acid + carbonate => Salt + water + carbon dioxide
What are limiting and excess reactants?
- Limiting reactant - The reactant that you have is less than you should actually have.
- Excess reactant- The reactant that you have more than you should have
What is conservation of mass?
The idea that in a chemical reaction mass is neither created or destroyes
