Chemistry (Acids and Alkalis)

Question 1

Ph scale

Answer 1

Shows amount of acid or alkali is in a solution.
0-6= acids
7= neutral
8-14= alkalis

Question 2

3 types of indicators?

Answer 2

Litmus, methyl orange and phenolphthalein

Question 3

The reaction between an acid and base is called neutralisation. It produces salt and water.

Answer 3

HCL + NaOH - NaCl + H2O

Acid Base Salt Water

Question 4

Neutralisation reactions in an aqueous solution can also be shown as an ionic solution in terms of H+ and OH- ions.

Answer 4

H+(aq) + OH- (aq) - H2O (l)

Question 5

Litmus-

Answer 5

Is red in acidic solutions, purple in neutral solutions and blue in alkaline.

Question 6

Methyl orange-

Answer 6

Is red in acidic solutions and yellow in neutral and alkaline solutions.

Question 7

Phenolphthalein-

Answer 7

Is colourless in acidic or neutral solutions and pink in alkaline solutions.

Question 8

Strong acids-

Answer 8

Ionise almost completely in water. They tend to have low pHs (pH 0-2)

Question 9

Weak acids-

Answer 9

Do not fully ionise in solution. Their pHs tend to be around 2-6.

Question 10

Polyatomic ions-

Answer 10

Are formed when small groups of atoms, held together by covalent bonds, lose or gain electrons.

Question 11

Acid + metal oxide = salt + water

Answer 11

Example:

2HCl + CuO = CuCl2 + H2O

Question 12

Acid + metal hydroxide = salt + water

Answer 12

Example:

HCl + NaOH = NaCl + H2O

Question 13

Acid + Metal = salt + hydrogen

Answer 13

Example:

2HCl + Mg = MgCl2 + H2

Question 14

Acid + metal carbonate = salt + water + carbon dioxide

Answer 14

Example:

2HCl + Na2Cl +H2O +CO2

Question 15

Concentration-

Answer 15

Basically how watered down your acid is.

Question 16

Bases are…

Answer 16

Substances that neutralise acids to form a salt and water only.

Question 17

Making soluble salts-

Answer 17

You can add copper oxide to warm sulphuric acid to make a solution of copper sulfate. If you evaporate off some of the water and leave this solution to crystallise, you should get lovely blue crystals of hydrated copper sulfate, which you can filter off and dry.

Question 18

To make a pure, dry salt:

Answer 18

Carry out titration
Note the exact volume of acid needed to neutralise the alkali.
Use the burette to add the correct volume of acid without the indicator.
Evaporate the water from the solution formed.

Question 19

How do you test for carbon dioxide?

Answer 19

Using limewater

Question 20

All salts are ionic. When two solutions containing soluble salts react together, the ions from the salts swap.

Answer 20

For example:
Copper sulfate + potassium carbonate=
Copper carbonate + potassium sulfate.