SALT PREPERATIONS [dchemlc]

According to the Bronsted-Lowry theory, an acid is a proton _________.

Answer explanation

• An acid is a proton (hydrogen ion) donor.

• A base is a proton (hydrogen ion) acceptor.

This is called the Bronsted-Lowry theory.

According to Arrhenius theory of acids and bases, an alkali is something that produces ________ions in solution.

• H⁺ _(aq)

• OH^- _(aq)

• Cl^-

• NH₄⁺

Answer explanation

An acid is something that produces H⁺_(aq) ions in solution and an alkali is something that produces

OH^-_(aq) ions in solution.

This is called the Arrhenius theory of acids and bases.

Which of the following carbonates are insoluble?

• Sodium carbonate

• Potassium carbonate

• Ammonium carbonate

• Calcium carbonate

Answer explanation

most common carbonates are insoluble, except sodium, potassium and ammonium carbonates.

Which of the following hydroxides are slightly soluble in water?

• Ammonium hydroxide

• Calcium hydroxide

• Magnesium hydroxide

• Lead hydroxide

Answer explanation

most metal hydroxides are insoluble (or almost insoluble), except sodium, potassium and ammonium hydroxides. Calcium hydroxide is slightly soluble in water.

Which of the following mixtures cannot be used to prepare a soluble salt?

• acid + metal  

• acid + metal oxide or hydroxide

• acid + carbonate.

• acid + water

Answer explanation

Preparation of soluble salts all involve reacting a solid with an acid.

• acid + metal (but only for the moderately reactive metals from magnesium to iron in the reactivity series)

• acid + metal oxide or hydroxide

• acid + carbonate.

Whatever mixture you use, the method is basically the same.

which of the following substances can react with dilute acids in the cold?

• Carbonates

• Magnesium

• Copper oxide

• Silver nitrate

Answer explanation

Carbonates react with dilute acids in the cold, and so does magnesium. Most other things that you are likely to come across need to be heated.

What is the colour of the precipitate formed in the given reaction?

Pb(N0₃)_{2 (aq)} + 2Nal_(aq) -------> Pbl _2(s) + 2NaNO_3(aq)

• yellow

• orange

• green

• brown

Answer explanation

We can use barium chloride solution and dilute sulfuric acid to prepare barium sulfate. What is the colour of this precipitate?

• white

• blue

• yellow

• green

Answer explanation

The barium sulfate is a white precipitate.

which of the following do we need to use in a titration to make sodium chloride crystals?

• HCl

• NaOH

• H₂SO₄

• BaCl₂

Answer explanation

NaOH(aq) + HCl(aq) -------> NaCl(aq) + H₂O(l)

When many salts form their crystals water from the solution becomes chemically bound up with the salt. What is this water called?

Answer explanation

this is called water of crystallization.