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