Chemical Changes

Question 1

What is the pH scale

Answer 1

• A measure of how acidic or alkaline a solution is

Question 2

How can the pH of a solution be measured

Answer 2

• Indicator
• pH probe

Question 3

What ion do acids contain whilst dissolved in water

Answer 3

• H+

Question 4

What ions do alkaline form whilst dissolved in water

Answer 4

• OH-

Question 5

What determines the strength of an acid

Answer 5

• How many acid particles dissociate to release H+ ions, the more particles dissociate and the more H+ ions, the stronger the acid

Question 6

What type of scale is the pH scale

Answer 6

• A 10x logarithmic scale

Question 7

What metal molecules (bases) react with acid to form salt and water

Answer 7

• Metal oxides and metal hydroxides

Question 8

What metal molecules react with acid to form salt, water and carbonate

Answer 8

• Metal carbonates

Question 9

How can you make soluble salts

Answer 9

• Using an acid an an insoluble base

Question 10

Reactivity series from least to most reactive

Answer 10

• Copper
• Hydrogen
• Iron
• Zinc
• Carbon
• Magnesium
• Calcium
• Lithium
• Sodium
• Potassium

Question 11

How can you determine the reactivity of a metal with acid

Answer 11

• By measuring the speed of the reaction through measuring the amount of bubbles produced per unit time

Question 12

What element is used in basic oxygen reduction

Answer 12

• Carbon

Question 13

What elements can be reduced with carbon

Answer 13

• Zinc
• Iron
• Copper

Question 14

Define oxidation reaction

Answer 14

• A displacement reaction where either oxygen is gained or electrons are lost

Question 15

Define reduction reaction

Answer 15

• A displacement reaction where oxygen is lost or electrons are gained

Question 16

What are ionic equations

Answer 16

• Equations that only show the particles that react and the products they form

Question 17

Define electrolyte

Answer 17

• A molten or dissolved ionic compound

Question 18

What happens at the cathode (-ve electrode) in electrolysis

Answer 18

• Positive ions in the electrolyte gather and become reduced

Question 19

What happens at the anode (+ve electrode) in electrolysis

Answer 19

• Negative ions in the electrolyte gather and become oxidised

Question 20

What happens during electroylsis

Answer 20

• An electric current is passed through an electrolyte
• The ions move towards the electrodes, where they react, and the compound decomposes
• This creates a flow of charge through the electrolyte due to the flowing ions
• As ions gain or lose electrons, they form the uncharged element and are discharged from the electrolyte

Question 21

Why can’t an ionic solid be electrolysed

Answer 21

• The ions are fixed in position and are unable to move

Question 22

What happens to positive metal ions in electroylsis

Answer 22

• Reduced to the element at the cathode

Question 23

What happens to negative non-metal ions in electrolysis

Answer 23

• Oxidized to the element at the anode

Question 24

What is cryolyte

Answer 24

• An aluminum based compound

Question 25

What happens differently with the products in electrolysis with an aqueous solution instead of molten

Answer 25

• H+ and (OH)- ions form at the cathode and anode respectively as well