Chemical Changes

Question 1

What are cancelled out in a half equations?

Answer 1

Spectators

Question 2

What is OIL RIG?

Answer 2

Oxidation
Is
Loss
Reduction
Is
Gain

Question 3

What do alkalis release when dissolved in water?

Answer 3

Hyrdoxide(OH-) ions

Question 4

What do acids release when dissolved in water?

Answer 4

Hydrogen (H+) ions

Question 5

How to name salts?

Answer 5

1st part - metal in compound used

2nd - comes from an acid

Question 6

When does a salt change to -ide or -ate?

Answer 6

When an ion is made

Question 7

What does a salt with an ending of -ate mean?

Answer 7

Oxygen is present in the negative ion

Question 8

What is titration for?

Answer 8

Find the concentration of a solution by reacting it with a solution of known concentration

Question 9

How does titration work?

Answer 9

Find the amount of acid/alkali needed to neutralise alkali/acid

Question 10

Method for titration question

Answer 10

1. Work out moles of the solution of known concentration
2. Use molar ratios form balanced to work out the moles of other solution
3. Calculate the concentration of the other solution using titration equation

Question 11

What is the concentration equation?

Answer 11

Moles/volume (mol/dm3)

Question 12

What is concentration?

Answer 12

Concentration is measure of n.o of particles per unit volume

Question 13

What is strength?

Answer 13

Strength is the measure of dissociation or ionisation of the acid or alkali in water

Question 14

What is the pH scale for?

Answer 14

The concentration of H+ ions in the solution

Question 15

What happens to the pH scale if the concentration of H+ ions increase by a factor of 10?

Answer 15

The pH scale decreases by 1

Question 16

What happens to strong acids water?

Answer 16

They dissociate fully

Question 17

What happens to weak acids in water?

Answer 17

They dissociate partially

Question 18

What will a more concentrated acid have more available to release?

Answer 18

Hydrogen ions

Question 19

What do reactions of acid involve?

Answer 19

The H+ ions reacting with other substances

Question 20

What happens if concentration of H+ ions is high?

Answer 20

The rate of reaction will be faster

Question 21

Why can a dilute solution of a strong acid have a similar pH and reactivity to a concentrated of a weak acid?

Answer 21

They have similar strengths

Question 22

Iysis

Answer 22

Breaking something up

Question 23

Electrolysis

Answer 23

Splitting a compound using electricity into their individual elements

Question 24

What are liquid and solution that can conduct electricity called ?

Answer 24

Electrolytes

Question 25

In what compound can electrolysis be performed on?

Answer 25

Ionic compounds

Question 26

What happens in electrolysis?

Answer 26

When a current is passed through the liquid or solution, the ions start to separate into elements. Positive ions move towards the negative electrode and the negative ions move toward the positive electrode.

Question 27

What is a positive electrode called and what does it attract?

Answer 27

They are called anode and attract anions

Question 28

What is a negative electrode called and what does it attract?

Answer 28

They are called cathode and attract cations

Question 29

What will be discharged at the negative electrode or cathode and what does it make the solid?

Answer 29

Metal (positive ions) and makes the solid metal

Question 30

What will be discharged at the positive electrode or anode and what does it make the solid?

Answer 30

Non-metal (negative ions) to make a gas, liquid or solid depending on the element

Question 31

What does PANIC stand for?

Answer 31

``` Postive Anions Negative Is Cathode ```

Question 32

What happens to the negative ions at the positive electrode?

Answer 32

The negative ions lose electrons (oxidation)

Question 33

What happens to the positive ions at the negative electrode?

Answer 33

The positive ions gain electrons (reduction)

Question 34

How to write 1/2 equation?

Answer 34

1. Write formulae of reactant and product 2. Adjust n.o of ions if needed 3. Count n.o of charges (Add enough electrons so that both sides have the same total n.o of charges)

Question 35

Why is aluminium important?

Answer 35

It resists effects of other elements and is lightweight

Question 36

What is cryolite used for?

Answer 36

To conduct electricity and to allow substances to dissolve in lower melting/boiling temp

Question 37

What is alumina ?

Answer 37

Aluminium oxide

Question 38

What does a pH probe do?

Answer 38

Measure pH electronically and accurately

Question 39

What does a salt ending with an ending of -ide mean?

Answer 39

Only one element in the negative ion

Question 40

What type of elements is electrolysis used for?

Answer 40

More reactive than carbon

Question 41

What causes a metal to be more reactive?

Answer 41

If it is easy for the metal to form positive ions

Question 42

Method for titration

Answer 42

1. Using a pipette and pipette filler , add a set of volume of alkali to conical flask and add 2 or 3 drops of indicator 2. Use funnel to fill burette with some acid of known concentration 3. Record the initial volume by looking at eye level at the substance 4. Use the burette and add the alkali a bit at time while swirling. Go slower when the end point is to be reached 5. The indicator changes colour when all alkali neutralised 6. Record the final volume of acid in the burette and use the measurements to calculate the volume of acid needed to neutralise the alkali

Question 43

Example of universal indicator

Answer 43

Phenolphthalein (pink to colourless)

Question 44

What happens when ions travel to the electrolyte?

Answer 44

A flow of charge

Question 45

What state should the ionic compound at and why?

Answer 45

In liquid form so the ions are able to move freely and conduct electricity

Question 46

Which are the halide ions?

Answer 46

Chlorine, bromine, iodine

Question 47

3 methods to check pH

Answer 47

- litmus paper - pH probe - pH scale (indicator)

Question 48

What is the universal indicator for?

Answer 48

To estimate pH of solution

Question 49

In a displacement reaction, what happens to the metal?

Answer 49

It becomes oxidised

Question 50

In a displacement reaction, what happens to the metal ion?

Answer 50

It becomes reduced

Question 51

If halide ions and hydroxide ions is present?

Answer 51

Halide ions are formed

Question 52

If no halide ions are present ?

Answer 52

Hydroxide ions are discharged and oxygen will be formed

Question 53

What are metals found in the earth's crust called?

Answer 53

Native metals