CHAPTER 5 CHEMICAL CHANGES

Question 1

Fizzing of lithium,sodium,pottasium,calcium,magneisum,zinc,iron and copper with water

Answer 1

Lithium-fizzing
Sodium- vigorous fizzing
Pottasium-violent fizzing
Calcium-slow fizzing
Magnesium-a few bubbles
Zinc,iron,copper- no reaction

Question 2

Lighted splint pops and Fizzing of magnesium,zinc,iron and copper with acids

Answer 2

Magnesium - fast fizzing and pop
Zinc - slow fizzinf and no pop
Iron - a few bubbles and no pop
Copper - nothing and no pop

Question 3

What is a displacement reaction

Answer 3

A more reactive metal displacing a less reactive netal from its aqueous solution

Question 4

What is oxidation

Answer 4

The loss of electrons

Question 5

What is reduction

Answer 5

The gain of electrons

Question 6

Order of elements that are found native in reactivity series lowest to highest

Answer 6

Platnium,gold,silver,copper,hydrogen

Question 7

Order of elements that are extracted from ores by reaction with carbon in reactivity series lowest to highest

Answer 7

Lead,tin,iron,zinc,(carbon,aluminium

Question 8

Order of elements that are extracted by electroylysis in reactivity series lowest to highest

Answer 8

Magnesium,calcium,sodium,pottasium

Question 9

Naming when you make salts
Acids
Bases
Alkali
Carbonate

Answer 9

Acids - ends with acid
Bases - ends with oxide(usually insolubale)
Alklai - ends with hydroxide (usually soluble)
Carbonate - end with carbinate

Question 10

Making salts simple equations names
AA-WS
BA-WS
CA-WCS
MA-SH

Answer 10

Alkali + acid - water + salt
Base + acid - water + salt
Carbon + acid - water + carbon + salt
Metal + acid - salt + hydrogen

Question 11

Universal indicator
Substance(weak or strong + type) + colour + pH number
(5 examples) with HCl vinegar water NaHCl2 NaOH

Answer 11

(Strong acid)HCl - red - 1
(Weak acid)Vinegar - orange 3
(Neutral) - water - light green - 7
(Weak alkali)NaHCl2 - dark green - 9
(Strong alkali)NaOH - dark blue - 12

Question 12

What’s the ph scale

Answer 12

The pH scale tells you how acidic or alkaline a solution is

Question 13

How can the pH of a solution be measured

Answer 13

pH meter or universal indicator

Question 14

3 example of strong acid
1-contains hydrogen
2- contains nitrogen
3- contains sulfur

Answer 14

Hydrochloric acid
Nitric acid
Sulfuric acis

Question 15

3 examples of weak acids
1-found in vinegar
2-found in citrus acids
3-found in fizzy drinks

Answer 15

Ethanoic acid
Citric acid
Carbonic acid

Question 16

Strong and weak acids and if they ionise

Answer 16

Strong acids ionise completely as more h+ ions in soloution

Weak acids partially ionise as less h+ ions in soloution and reaction is reversable

Question 17

Makimg a copper salt method

Answer 17

1-Using a measuring cylinder, measure 20 cm3 of sulfruic acid into the beaker.

2-Stand the beaker on a tripod and gauze and warm gently until it is almost boiling. Turn off the Bunsen burner.

3-Add half a spatula of copper(II) carbonate powder into the acid and stir using the glass rod

4-Continue adding the copper(II) carbonate until no more dissolves. When the copper(II) carbonate
disappears the solution is clear blue.

5-Allow the apparatus to cool completely and then filter the mixture and discard the residue

6-Pour the filtrate into an evaporating basin. Evaporate this gently using a water bath (250cm3 beaker with boiling water) on the tripod and gauze (see diagram). Stop heating once crystals start to form.

7-Remove the evaporating basin from the heat and leave to crystallise.

8-Record what you observed when:
• Copper(II) carbona was first added to the acid.
• Excess copper(II) carbonate was added.
• The salt was left to crystallise.

Question 18

Conclusion of making a copper salt RP

Answer 18

Copper(II) carbonate was first added to the acid-
Colour changed to blue with fizzing and bubbiling

Excess copper(II) carbonate was added-
Stopped disolving so then undissolved solid bits floating at bottom

The salt was left to crystallise-
Blue rhombic(diamond shape) crystals of copper(II) sulfate