Chemical Changes

Question 1

From what pH’s is an acidic solution ?

Answer 1

0-6 pH

Question 2

What pH is a neutral solution ?

Answer 2

7

Question 3

What pH is a more alkaline solution?

Answer 3

8-14

Question 4

How can you measure the pH of a solution ?

Answer 4

1) An indicator - use universal indicator to determine the pH. Add the dye to the solution and then compare to a pH chart
2) pH probe - attached to a pH meter and is measured electronically . A more accurate way of testing the pH

Question 5

What type of ions do acids form in water ?

Answer 5

H+ ions

Question 6

A base is a substance with a pH greater than ..

Answer 6

7

Question 7

What type of ions does an alkaline in water make ?

Answer 7

OH- ions

Question 8

A reaction between an acid and a base is called what …

Answer 8

A neutralisation reaction

Question 9

What is the symbol equation for the neutralisation reaction ?

Answer 9

H+ (aq) + OH-(aq) = H20

Question 10

Strong acids do what in water ?

Answer 10

Completely ionise

Question 11

Weaker acids do not do what in water ?

Answer 11

Ionise completely

Question 12

If the concentration of a H+ ion is higher …

means what for stronger and weaker acids

Answer 12

The rate of reactions will be faster so strong acids react faster than the weaker acid at the same concentration

Question 13

What is the general formula to find the concentration of H+ ions from the pH?

Answer 13

Factor H+ ion concentration changes by = 10^(-X)

X = is the difference in the pH

Question 14

An acids strength tells you what ?

Answer 14

The proportion of acid molecules ionise in water

Question 15

The concentration of an acid tells you what ?

Answer 15

How much acid there is in a certain volume

Question 16

X + Y = Salt + Water

What are X & Y ?

Answer 16

1) X = Acid
Y = Metal Oxide

2) X= Acid
Y= Metal Hydroxide

Question 17

Acid + Metal Carbonate = X + Y + Z

What are X , Y and Z?

Answer 17

X Salt
Y Water
Z Carbon Dioxide

Question 18

What does the reactivity series base how reactive the metals are ?

Answer 18

How easily they lose their electrons

The higher up the list they Are the more reactive

Question 19

What is in the reactivity series ?

Answer 19

Potassium 
Sodium 
lithium 
Calcium 
Magnesium 
Carbon 
Zinc 
Iron 
Hydrogen 
Copper

Question 20

When a metal reacts with an acid how can you tell the sped of the reaction ?

Answer 20

How quickly hydrogen bubbles are given off 
Temperature Change (mass & surface area have to be the same )

Question 21

Metal + Water = X + Y

What are X&Y?

Answer 21

X. Metal hydroxide

Y. Hydrogen

Question 22

Metals react with oxygen to form oxides . What do they metals need to be extracted from and what sort of a reaction is it ?

Answer 22

Ores

Oxidation

Question 23

What are the two ways to separate metals from their oxides ?

Answer 23

Oxidation

Reduction

Question 24

What does OIL RIG Stand for ?

Answer 24

OIL - oxidation is lose of electrons ( and gain of oxygen )

RIG - reduction is gain of electrons ( and lose of oxygen )

Question 25

Metal with higher reactivity have to be extracted by what and what are these metals ?

Answer 25

Electrolysis

Potassium , sodium , lithium , calcium , magnesium

Question 26

The less reactive metals are extract by what and what are these metals ?

Answer 26

Reduction using carbon & blast furnace ?

Zinc , iron , copper

Question 27

What is a redox reaction ?

Answer 27

When oxidation and reduction happens at the same time

Question 28

What is the rule for a displacement reaction ?

Answer 28

A more reactive metal will always displace a less reactive metal from its compound

Question 29

In dis placement reaction what happens to the metal ion and what happens to a metal atom ?

Answer 29

The metal ion gains electrons and is reduced

The metal atom loses electrons and is oxidised

Question 30

What happens during electrolysis ?

Answer 30

1) an electric current is passes through an electrolyte ( liquid or solution that can conduct electricity/ a molten or dissolved ionic compound ). The ions move towards the electrodes ( a solid that can conduct electricity and is submerged in the electrolyte) , where they will react and the compound will decompose.
2) Positive ions in the electrolyte will move towards the cathode (-ve) and gains electrons - reduction
3) Negative ions move towards the anode (+ve) and lose electrons -oxidation
4) This creates a flow of charge
5) The uncharged element will be discharge from the electrolyte

Question 31

Why can’t an ionic solid be electrolysed ?

Answer 31

Because the ions are in fixed positions and can’t move ?

Question 32

During electrolysis positive metal ions are …. And Negative
non - metal ions are …..

Answer 32

Positive metal ions are reduced at the cathode

Negative non - metal ions are oxidised at the anode

Question 33

In aqueous solutions there will be what type of ions from the water ?

Answer 33

Hydrogen ions and Hydroxide ions

Question 34

During electrolysis os an aqueous solution at the cathode , if H+ ions and and metal ions are present what will be produced if what happens ?

Answer 34

Hydrogen if the metal ions form an elemental element which is more reactive than hydrogen
However If the elemental metal is less reactive than hydrogen the a pure metal is produced instead

Question 35

What do half equations show ?

Answer 35

Show the reactions at the electrodes