Chapter 18 Flashcards
Test for hydrogen
Put out lighted splint with squeaky pop
Equation for hydrogen test
2H2*O2-> 2H20
Test for oxygen
Glowing splint relights
Test for Carbon Dioxide
Bubbled through limewater
Equation for Carbon Dioxide
Ca(OH)2(aq)+CO2(g)+CO2(g) —> CaCO3(s)+H2O(l)
Test for Chlorine
Blue litmus paper turns red then bleaches white
Test for ammonia
Red litmus paper turns blue
Test for water
White anhydrous copper sulphate would turn blue
Equation for water test
CuSO4+5H2O—>CuSO4.5H2O
left: anhydrous, right: hydrated
Flame tests can be used to identify what?
metal ions eg lithium, sodium, potassium, calcium and compounds
How do flame tests work?
- Dip the flame test wire into concentrated hydrochloride acid then hold it in the non-luminous (blue) Bunsen flame to clean it
- Dip the wire back into the acid then into the solid being tested
- Hold the wire in the non-luminous flame
Lithium ion colour
Red/ crimson
Sodium ion colour
Yellow
Potassium ion colour
Lilac
Calcium ion colour
Orange - red
Copper ion colour
Blue green
Testing for positive ions using sodium hydroxide how:
- add a few drops of sodium hydroxide solution to the solution being tested
Why does the sodium hydroxide test work?
Most metal hydroxides are insoluble and transition metal ions form coloured precipitates with sodium hydroxide
Copper Sulphate + Sodium hydroxide —>
Copper hydroxide + sodium sulphate
