1acids, bases and salt preparations

Question 1

ionic compounds are

Answer 1

generally soluble in water compared to covalent substances, however there are exceptions

Question 2

soluble ionic compounds

Answer 2

compounds of sodium potassium and ammonia, all nitrates, all chlorides except silver and lead (II), all sulfates except barium, calcium and lead(II), sodium potassium and ammonium carbonates, sodium potassium and calcium hydroxides

Question 3

insoluble ionic compounds

Answer 3

silver and lead (II), barium calcium and lead (II), all other carbonates except sodium potassium and ammonium carbonates, all hydroxides except sodium potassium and calcium hydroxide

Question 4

calcium hydroxide is

Answer 4

slightly soluble in water

Question 5

acids in terms of proton transfer

Answer 5

acids are proton donors as they ionise in solution producing protons, H^+ ions, these H^+ ions make aqueous solution acidic

Question 6

bases in terms of proton transfer

Answer 6

bases are proton accepters as they ionise in solution producing OH^- ions which can accept protons, these OH^- ions make the aqueous solution alkaline

Question 7

only metals above

Answer 7

hydrogen in the reactivity series will react with dilute acids

Question 8

the more reactive a metal is

Answer 8

the mire vigorous the reaction will be

Question 9

metals that are placed high on the reactivity series are

Answer 9

very dangerous and react explosively with acids

Question 10

when acids react with metals they form

Answer 10

a salt and hydrogen gas

Question 11

general equation for a metal and salt and hydrogen gas reaction

Answer 11

metal + acid -> salt + hydrogen

Question 12

when an acid reacts with a base a

Answer 12

neutralisation reaction occurs

Question 13

acid base neutralisation equation

Answer 13

acid + base -> salt + water

Question 14

the identity of a salt produced depends on

Answer 14

the acid used and the positive ions in the base

Question 15

hydrochloric acid produces

Answer 15

chloride

Question 16

sulfuric acid produces

Answer 16

sulfate salts

Question 17

nitric acid produces

Answer 17

nitrates

Question 18

metal oxides and metal hydroxides act as

Answer 18

bases

Question 19

acids will react with metal carbonates to form the

Answer 19

corresponding metal salt, carbon dioxide and water

Question 20

bases are

Answer 20

substances which can neutralise an acid forming salt and water

Question 21

in alkaline conditions red litmus paper turns

Answer 21

blue

Question 22

bases are usually

Answer 22

oxides, hydroxides or carbonates of metals

Question 23

the presence of the OH^- ions is what

Answer 23

makes the aqueous solution an alkali

Question 24

how to prepare a soluble salt from the reaction of an acid with an insoluble base

Answer 24

During the preparation of soluble salts, the insoluble reactant is added in excess to ensure that all of the acid has reacted
If this step is not completed, any unreacted acid would become dangerously concentrated during evaporation and crystallisation
The excess reactant is then removed by filtration to ensure that only the salt and water remain
Since all of the acid has reacted and the excess solid base has been removed then the solution left can only be salt and water
If a carbonate was used as the solid base instead of an oxide or hydroxide, then any carbon dioxide gas produced would have been released into the atmosphere
A common example is the preparation of copper(II) sulfate which can be made with copper(II) oxide and dilute sulfuric acid:
CuO (s) + H2SO4 (aq) ⟶ CuSO4 (s) + H2O (l)

The acid could also be reacted with a metal to produce the salt, as long as the metal is above hydrogen in the reactivity series and not too reactive so that a dangerous reaction does not take place

Question 25

materials needed to prepare copper (II) sulfate

Answer 25

1.0 mol / dm3 dilute sulfuric acid
Copper(II) oxide
Spatula & glass rod
Measuring cylinder & 100 cm3 beaker
Bunsen burner
Tripod, gauze & heatproof mat
Filter funnel & paper, conical flask
Evaporating basin and dish.

Question 26

method to prepare copper (II) sulfate

Answer 26

Add 50 cm3 dilute acid into a beaker and warm gently using a Bunsen burner
Add the copper(II) oxide slowly to the hot dilute acid and stir until the base is in excess (i.e. until the base stops dissolving and a suspension of the base forms in the acid)
Filter the mixture into an evaporating basin to remove the excess base
Gently heat the solution in a water bath or with an electric heater to evaporate the water and to make the solution saturated
Check the solution is saturated by dipping a cold glass rod into the solution and seeing if crystals form on the end
Leave the filtrate in a warm place to dry and crystallise
Decant excess solution and allow the crystals to dry

Question 27

results of preparing copper (II) sulfate

Answer 27

Hydrated copper(II) sulfate crystals should be bright blue and regularly shaped