Tests For Cations Flashcards
What are cations?
- positive ions
- metal ions
How do you carry out a flame test?
- nichrome wire dipped in water/HCl
- then dipped in substance
- substance put into flame
During the flame test, what colour does lithium go?
Crimson
What is the ion for lithium?
Li+
During the flame test, what colour does sodium go?
Yellow
What is the ion for sodium?
Na+
During the flame test, what colour does potassium go?
Lilac
What si the ion for potassium?
K+
During the flame test, what colour does calcium go?
Brick red
What is the ion for calcium?
Ca2+
During the flame test, what colour does copper go?
Green
What is the ion for copper?
Cu2+
During the flame test, what colour does barium go?
Apple green
What is the ion for barium?
Ba2+
What happens if a mixture is flame tested?
Flame colours masked making it hard to differentiate
What are precipitates?
Insoluble solids
When sodium hydroxide is added to copper solution, what coloured precipitate forms?
Blue precipitate
When sodium hydroxide is added to iron (II) solution, what coloured precipitate forms?
Green precipitate
What is the ion for iron (II)?
Fe2+
When sodium hydroxide is added to iron (III) solution, what coloured precipitate forms?
Red-brown precipitate
What is the ion for iron (III)?
Fe3+
When sodium hydroxide is added to magnesium solution, what coloured precipitate forms?
White
What is the ion for magnesium?
Mg2+
When sodium hydroxide is added to calcium solution, what coloured precipitate forms?
White
What is the ion for calcium?
Ca2+
When sodium hydroxide is added to aluminium solution, what coloured precipitate forms?
White
What ion for aluminium form?
Al3+
What is happens when an excess of NaOH is added to aluminium solution?
White precipitate dissolves
