Acids, Bases and Salts

Question 1

Why is Litmus paper not very accurate

Answer 1

Litmus paper is not very accurate as it cannot differentiate between strong and weak. Also, red litmus paper does not distinguish between acid and neutral. Blue litmus does not distinguish between alkali and neutral.

Question 2

Why is universal indicator a better indicator

Answer 2

Universal indicator is more accurate as it distinguishes between strong and weak

Question 3

How is universal indicator tested

Answer 3

Universal indicator can either be used as a solution that is dropped into the substance being tested. Or as a paper that is dipped into the substance being tested. The colour that the substance turns is then compared with the pH colour chart, to determine a number value of pH

Question 4

What is the best way to measure pH

Answer 4

The best way to measure pH with a pH meter It measures pH to at least one decimal place in the solution and the digital reading is recorded to one decimal place The pH meter is placed

Question 5

Give a solution for pH 0-2 strong acid

Answer 5

Nitric acid
Hydrochloric acid
Sulfuric acid

Question 6

Give a solution for pH 3-6 weak acid

Answer 6

vinier
ethanoic acid
carbonic acid

Question 7

Give a solution for pH 7 neutral

Answer 7

water
sodium nitrate
sodium chloride

Question 8

Give a solution for pH 8-11 weak alkali

Answer 8

ammonia

Question 9

Give a solution for pH 12-14 strong alkali

Answer 9

sodium hydroxide

Question 10

What is an Acid

Answer 10

An acid is a substance that dissolves in water producing hydrogen ions (H+(aq))

Question 11

What is an Alkali

Answer 11

An alkali is a substance that dissolves in water producing hydroxide ions (OH-(aq))

Question 12

What’s the difference between strong and weak acids

Answer 12

strong acids are acids that are completely ionised in water and weak acids are acids that are partially ionised in water

Question 13

What’s the difference between strong and weak alkali

Answer 13

strong alkali are alkali that are completely ionised in water and weak alkali are alkali that are partially ionised in water

Question 14

What’s the difference between diluted and concentrated solutions

Answer 14

A concentrated solutions contains a large number of acid particles dissolved per unit volume. A diluted solutions contains a small number of acid particles dissolved per unit volume

Question 15

What is a base

Answer 15

A base is a substance that can neutralize the acid by reacting with hydrogen ions. Most bases are minerals that react with acids to form water and salts.

Question 16

What is neutralisation

Answer 16

neutralisation is a chemical reaction in which acid and a base react with an equivalent quantity of each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution.

Question 17

What is the neutralisation equation

Answer 17

H+(aq) + OH-(aq) → H2O(l)

Question 18

What is all the neutralisation word equations

Answer 18

1. Acid + Alkali → Salt + Water
2. Metal + Acid →Salt + Hydrogen
3. Metal Carbonate + Acid →Salt + Water + Carbon-Dioxide or Metal Hydrogen carbonate + Acid →Salt + Water + Carbon-Dioxide
4. Acid + Ammonia →Ammonia Salt

Question 19

What are the 4 important salt

Answer 19

Nitric acid (HNO₃) nitrate
Hydrochloric acid (HCl) chloride
Sulfuric acid (H₂SO₄) sulfate
Ammonia (NH3) ammonium

Question 20

What does an exothermic reaction mean

Answer 20

An exothermic is one which heat is given out

Question 21

Are neutralisation reactions exothermic

Answer 21

YES

Question 22

Step by step for what is happening during a endothermic neutralisation reactions

Answer 22

If you added an acid and an alkali together in a beaker, with a thermometer. You would see the temperature rising an the thermometer and feel the beaker warming up.

Question 23

Why is a polystyrene cup used instead of a beaker in the neutralisation reactions

Answer 23

because a polystyrene cup is an insulator

Question 24

How can hydrogen be tested

Answer 24

Apply a lighted splint
A popping sound result

Question 25

How can carbon dioxide be tested

Answer 25

Bubble the gas into colourless limewater (calcium hydroxide solution)
The solution will change to milky if the gas is carbon dioxide

Question 26

What are some observations for acid reactions

Answer 26

• If a gas is produced the observation is ‘bubbling’

-If a solid (such as a solid metal, base or carbonate) reacts with the acid then the observation is ‘solid disappears and a solution is produced’

-Most acid reactions are exothermic (heat given out) the observation is ‘heat released’. Two exceptions to this: are reactions with copper(II) oxide and sodium hydrogen carbonate

Question 27

Colour observations for Copper(II) Oxide

Answer 27

Black solid

Question 28

Colour observations for Copper(II) Carbonate

Answer 28

Green solid

Question 29

Colour observations for Hydrated Copper(II) Sulfate

Answer 29

Blue crystals

Question 30

Colour observations for salts in solutions

Answer 30

Blue solutions

Question 31

Colour observations for group 1, group 2, aluminium and zinc compounds

Answer 31

White solids
give a colourless solution when dissolved

Question 32

Observations you need for your answer for Acid and Metal

Answer 32

Bubbles, Heat is released, Solid disappears and Colourless solution formed

Question 33

Observations you need for your answer for Acid and Copper carbonate

Answer 33

Bubbles, Heat is released, Solid disappears and Blue solution formed

Question 34

Observations you need for your answer for Acid and Sodium Carbonate

Answer 34

Bubbles, Heat is released, Solid disappears and Colourless solution formed