Testing for Metal Ions and Ammonium Ion

This lesson covers testing for transition metal ions and the ammonium ion. It explains how to use a flame test for group 1 and 2 metal ions and copper ions. Transition metal ions are tested by adding sodium hydroxide to form colored precipitates, which help identify the ions. The lesson also discusses the oxidation of iron(II) hydroxide to iron(III) hydroxide, causing a color change. Non-transition metal ions like calcium, aluminum, and magnesium form white precipitates with sodium hydroxide. The ammonium ion test involves adding sodium hydroxide and warming, producing ammonia, which is detected with litmus paper or hydrochloric acid.

Which test is used to identify group 1 and group 2 metal ions?

• Smoke test

• Flame test

• Precipitation test

• Litmus test

What color precipitate does copper(II) hydroxide form?

• Green

• Reddish brown

• Blue

• White

What is the color of zinc hydroxide precipitate?

• Green

• Blue

• White

• Reddish brown

What is the general reaction equation for forming a metal hydroxide precipitate?

• Metal ion + water = metal hydroxide

• Metal ion + acid = metal salt

• Metal ion + hydroxide ion = metal hydroxide

• Metal ion + oxygen = metal oxide

Why does iron(II) hydroxide change color upon standing?

• It reacts with water

• It absorbs carbon dioxide

• It oxidizes to iron(III) hydroxide

• It decomposes into iron and oxygen

Which metal ion gives a brick red flame in a flame test?

• Aluminum

• Calcium

• Magnesium

• Zinc

What happens to aluminum hydroxide upon further addition of sodium hydroxide?

• It forms a blue precipitate

• It remains unchanged

• It dissolves

• It turns green

Which of the following ions does not give a flame color?

• Magnesium

• Copper

• Calcium

• Iron

How can the presence of ammonia be detected when testing for ammonium ions?

• By a sweet smell

• By turning red litmus paper blue

• By a color change to red

• By forming a green precipitate

What is formed when a glass rod dipped in concentrated hydrochloric acid is held near the reaction vessel containing ammonium ions?

• Ammonium nitrate

• Ammonium chloride smoke

• Ammonium sulfate

• Ammonium carbonate