C3 Flashcards
What is hard water?
water that contains dissolved mg2+ or ca2+ ions. The ions enter the water when slightly acidic rain (formed by dissolved co2)flows over rocks containing magnesium/calcium carbonate or magnesium/calcium sulphate.
What are the different types of hardness?
Temporary and Permanent
What does temporary hard water contain?
Ca2+/mg2+ and HCO3- ions
How can the hardness be removed by heating the temporary hard water?
Ca2+ + HCO3- = CaCO3 + H2O + CO2
aq aq solid liquid gas
What does permanent hard water contain?
Ca2+/Mg2+ and SO42- ions
How can the hardness be removed by heating the permanent hard water?
By adding Na2CO3. Na+ ions replace Ca2+ ions in the solution forming insoluble precipitate calcium carbonate
In group 1 (alkali metals) describe the denseness?
Goes from most to least dense
What are the patterns of the group 7 elements (halogens)?
Increases in boiling point as you go down
Goes from lightest to darkest
What are transition metals like compared to group 1 and 2 metals?
unreactive high melting points (apart from mercury) strong and hard high density makes coloured compounds are as useful as catalysts
In the chemical test when testing for aluminium, calcium and magnesium, what chemicals or conditions are required?
sodium hydroxide
In the chemical test when testing for aluminium, calcium and magnesium, what is the positive result?
if a white precipitate is formed, it means that it could be Al, Cl, or Mg but if when more is added it dissolves, its Al
In the chemical test when testing for chloride, bromide, iodide, what chemicals or conditions are required?
silver nitrate solution and dilute nitric acid
In the chemical test when testing for chloride, bromide, iodide, what is the positive result?
Cl- =white precipitate
Br-=cream precipitate
I-=yellow precipitate
In the chemical test when testing for carbonate ions what chemicals or conditions are required?
Dilute hydrochloric acid and bubble any gas produced through limewater
In the chemical test when testing for carbonate ions, what is the positive result?
limewater turns cloudy
In the chemical test when testing for iron (ii) iron (iii) and copper (ii), what chemicals or conditions are required?
add sodium hydroxide
In the chemical test when testing for iron (ii) iron (iii) and copper (ii), what is the positive result?
Fe2+ = green precipitate Fe3+ = brown precipitate Cu2+ = blue precipitate
In the chemical test when testing for lithium, sodium, barium, potassium and calcium what chemicals or conditions are required?
Add sample to roaring flame
In the chemical test when testing for lithium, sodium, barium, potassium and calcium what is the positive result?
lithium = crimson sodium = yellow barium = green potassium = lilac calcium = red
In the chemical test when testing for sulphate,what chemicals or conditions are required?
Add dilute hydrochloric acid and barium chloride
In the chemical test when testing for sulphate, what is the positive result?
White precipitate
What are the rules of equilibria: (le chatlier’s principal)
- high temperature favours endothermic reaction
- low temperatures favours the exothermic reaction
- increasing reactants favours forwards reaction
- decreasing products favours forward reaction
- high pressure favours side with fewest moles
- low pressure favours side with most moles
How do you work out the overall enthalpy/energy change for the reaction?
Sum (bonds broken) - sum(bonds made) = energy change
What are the ideal conditions for the haber reaction?
Low temperature
High pressure
Constant supply of Ne and H2
Remove the products
So why are the conditions of the equilibria reaction 450 degrees and 200 atms?
450 is a compromise between the yield of the reaction and the rate of reaction
200 atms is used as extremely high pressures could explode
What is dynamic equilibrium?
Most reactions are reversible to some degree
If a system is in dynamic equilibrium then the rate of the forward reaction is the same as the rate of the reverse reaction
This means the concentrations of reactions and products do not change
How is ammonia made
Haber process
What is the molecular formula of methanoic acid?
HCOOH
What is the molecular formula of ethanoic acid?
CH3COOH
What is the molecular formula of propanoic acid?
CH3CH2COOH
