Acids, Bases And Salts

Question 1

Indicator definition

Answer 1

It is a chemical that gives a colour change in acidic, alkaline and neutral solutions

Question 2

What colour will red and blue litmus paper turn in acid, neutral and alkali solution

Answer 2

Red - Acid: red Neutral: red Alkali: blue
Blue - Acid: red Neutral: blue Alkali: blue

Question 3

Phenolphthalein indicator and Methyl orange indicator colours

Answer 3

Acid - P: colourless M: red
Neutral - P: colourless M: orange
Alkali - P:Pink M: Yellow

Question 4

How do you know if an acid is strong or weak

Answer 4

A strong acid completely ionises in water where weak acids only partially ionise
Lots of hydrogen = strong acid
Fewer hydrogen = weak acid

Question 5

What is a base?

Answer 5

It is a substance that will react with an acid producing a salt and water (metal oxides and hydroxides).
Alkalis are soluble bases

Question 6

What is a concentrated acid?

Answer 6

It contains a large number of acid particles dissolved per unit volume

Question 7

What is a dilute acid?

Answer 7

It contains a small number of acid particles dissolved per unit volume

Question 8

Neutralisation definiton

Answer 8

It is the reaction between an acid and an alkali to producing a salt and water.
These reactions are exothermic

Question 9

Ionic equation for neutralisation

Answer 9

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

Question 10

Salt definition

Answer 10

It is the compound formed when some or all of the hydrogen ions in an acid are replaced by metal ions or ammonium ions

Question 11

General rule for oxides

Answer 11

Metal oxides are basic & non metal oxides are acidic

Question 12

Colour of copper (ll) oxide and copper (ll) carbonate

Answer 12

Copper oxide- black solid
Copper carbonate - green solid

Question 13

Colours of hydrated copper (ll) sulfate and copper (ll) salts in solution

Answer 13

Copper sulfate - blue crystals
Copper salts in solution - blue solution

Question 14

Two methods of drying crystals

Answer 14

Low temp oven or in a desicator

Question 15

How to form a salt using a insoluble metal carbonate and an acid?

Answer 15

Put 25Cm3 into a beaker and heat it up.
Add the carbonate and keep adding it until there is no further reaction.
Filter the mixture into an evaporating basin and heat it until it is a half volume.
Allow the basin to cool and crystals will form.

Question 16

Method for preparing a salt from acid and soluble base

Answer 16

Fill a burette with hydrochloric acid and add 3 drops of phenolphthalein to a conical flask.
Add the hydrochloric acid into the conical flask and stop when the indicator turns colourless.
Record the volume by carefully reading the burette.
Do this without the indicator and place the solution into an evaporating basin and heat until it is half volume.
Leave to cool and crystallise.

Question 17

Method for neutralisation reaction?

Answer 17

1. Place 20cm3 of alkali into a conical flask
2. Fill a burette with 40cm3 of acid
3. Measure the pH and the temp of solution
4. Add 4cm3 of the acid to the alkali
5. Mix the reagents and measure the pH and temp of the solution
6. Repeat steps 4&5 until a total of 40cm3 of acid has been added

Question 18

Method for preparing soluble salt from acid and metal

Answer 18

1.25cm3 of acid is put in a beaker and metal is added. Metal begins to dissolve and hydrogen bubbles are given off. More zinc is added until bubbles stop
2. Excess zinc left over is removed by filtering. An aqueous solution of zinc sulfate is collected in an evaporating dish
3. The solution is heated to evaporate some of the water, heating stopped once crystals of salt are seen to form around edges of basin
4. At this point the solution is left to cool