Ch 1.3 Identification of Ions

Given the equation: Zn (s)     +     2HCl (aq)     →     ZnCl₂ (aq)     +     H₂ (g)

Which of the following is the correct ionic equation?

• Zn (s)     +     2H⁺ (aq)     →     Zn²⁺ (aq)     +     H₂ (g)

• Zn (s)     +     2HCl (aq)     →     Zn²⁺ (aq)     +     H₂ (g)

• Zn2+ (s)   +   2HCl (aq)    

  →     ZnCl (aq)  +  H+(g)

A metallic ion in aqueous solution produces

·     a white precipitate with aqueous ammonia, soluble in excess;

·     a white precipitate with aqueous sodium hydroxide, soluble in excess.

 

• Ca²⁺

• K⁺

• Pb²⁺

• Zn²⁺

An aqueous solution of compound X reacts with aqueous sodium hydroxide to form a green precipitate and then aluminium powder is added. The mixture is heated and a gas that turns damp red litmus paper blue is given off. What is X?

• ammonium nitrate

• copper(II) chloride

• iron(III) chloride

• iron(II) nitrate

Which two gases each change the colour of damp red litmus paper?

• ammonia and chlorine

• ammonia and hydrogen chloride

• carbon dioxide and chlorine

• carbon dioxide and sulfur dioxide

Consider the flow chart as shown. What is the white precipiate C?

Name A.

Name B.

Name C.

Answer explanation

Remember to include roman numerals for Copper, lead and iron

Study the reaction scheme shown. Identify solution Q.

• ammonium nitrate

• aqueous ammonia

• dilute nitric acid

• sulfuric acid

Answer explanation

Nitrate is present as it gives off ammonia gas upon reaction with warm NaOH and aluminium foil.

A farmer heated some fertiliser with aqueous sodium hydroxide. A gas was given off which turned damp red litmus paper blue. He then dissolved some of the fertiliser in water. On adding dilute nitric acid and aqueous barium nitrate, a white precipitate was formed.

What salt did the fertiliser contain?

• ammonium nitrate

• ammonium sulfate

• potassium nitrate

• potassium sulfate

Answer explanation

ammonium test: on warming with excess aqueous sodium hydroxide, evolved a gas that turned damp red litmus paper blue. [NH₃]

Sulfate test : by reaction of an aqueous solution with nitric acid and aqueous barium nitrate