quantitative and qualitative chemistry Flashcards
Avogadro’s constant
the number of particles in 1 mole = 6 × 10^23 mol−1
conversion of tonnes to kg and g
1 tonne = 1000kg = 1,000,000g
empirical formula
- the simplest whole number ratio of atoms of each element present in a compound
- can be determined from the % composition of mass of the elements present in the compound
- formula: (mass or %mass / Mr) for both elements, then simplify ratio
molecular formula from empirical formula
do Mr of molecular formula / Mr of empirical formula, then multiply empirical formula by answer
molar volume of gases at room temp and pressure
24lmol-1
formula for mass of solute
mass of solute (in g) = conc. (in gL-1) x volume (in L)
relationship between temp and solubility
- as temp increases, solubility of salts increases
- as temp increases, solubility of gases decreases
%yield =
(actual yield / theoretical yield) x 100
why is it not always possible to obtain the theoretical mass of a product
- the reaction will not go to completion if it is reversible
- some of the product may be lost when it is separated from the reaction mixture
- some of the reactants may also react in ways different to the expected reaction
1 dm3 (dm cubed) =
1 litre
test for hydrogen gas
-hydrogen burns with a squeaky pop
test for oxygen gas
-oxygen relights a glowing splint
test for carbon dioxide gas
- carbon dioxide turns limewater cloudy
- this is due to the insoluble suspension of calcium carbonate (precipitate) formed
reactivity series
- potassium PETER
- sodium SMITH
- lithium LUCKILY
- calcium CAUGHT
- magnesium MY
- aluminium AUNT
- carbon CATHERINE
- zinc ZINA
- iron IN
- tin THE
- lead LARDER
- hydrogen HIDDEN
- copper CAREFULLY
- mercury MUNCHING
- silver SOME
- gold GREEN
- platinum PEAS
test for chlorine gas
-litmus (pH) paper turns red then white
flame tests Li = Na= K= Ca= Cu=
- Li – crimson red
- Na – yellow-orange
- K – lilac
- Ca – red-orange
- Cu – green
concentration formula
conc = (mass of solute in grams) / (volume of solution in litres)
1 decilitre (dL) =
100ml / 0.1L
test for halide ions (Cl-, B-, I-)
- add dilute nitric acid and a few drops of silver nitrate solution to the unknown solution
- halide ions will precipitate as silver halides
- each silver halide precipitate has a distinctive colour:
- silver iodide = yellow
- silver bromide = cream
- silver chloride = white
test for sulfate ions
- addition of dilute HNO3 / HCl to the unknown solution, followed by a solution of barium nitrate/chloride
- a white precipitate indicates the presence of sulfate ions.
test for carbonate ions
-carbonate ions react with an acid to release CO2 gas
order of tests for anions
If the anions present in a sample is unknown, test in this specific order:
1) carbonate ions
2) sulfate ions
3) halide ions
flame tests (testing for cations)
- thin wire is washed in a little acid, then dipped into the unknown substance
- wire is placed in the blue flame of a Bunsen burner
lithium: crimson red
sodium: yellow-orange
potassium: lilac
calcium: red-orange
copper: green
test for water
-copper(II) sulfate solid is white when anhydrous but blue when hydrated
1m3 =
1000litres
iron colours
Fe2+ = green Fe3+ = orange-brown
lead valency
+2
zinc valency
+2
