Chapter 5

Question 1

How many particles are there in 1 mole?

Answer 1

6.02 x 10^23

Question 2

What is Avagadro’s constant?

Answer 2

The number of particles in 1 mole

Question 3

What is the formula for the number of moles in terms of particles?

Answer 3

Moles = number of particles you have / Avagadro’s constant

Question 4

What is the molar mass?

Answer 4

The mass per mole of something

Question 5

Is the molar mass the same as the relative molecular mass?

Answer 5

Yes

Question 6

What is the equation for moles in terms of molar mass?

Answer 6

Moles = mass of substance / molar mass of substance

Question 7

What is the equation for moles in terms of concentration?

Answer 7

Moles = concentration x volume

Question 8

What is concentration usually measured in?

Answer 8

Moles / dm^3

Question 9

What does the empirical formula give you?

Answer 9

The smallest whole number ratio of atoms

Question 10

What does the molecular formula give you?

Answer 10

The actual number of atoms in each type of elements in a molecule

Question 11

What is the percentage composition of an element?

Answer 11

(The total mass of the element in a compound / total mass of compound) X 100

Question 12

What do ionic equations show?

Answer 12

The reacting particles only

Question 13

How do you work through an ionic eqution?

Answer 13

Rewrite the equation to just the ions, cross out any ions that are the same on both sides

Question 14

What happens in a displacement reaction?

Answer 14

On element replaces another

Question 15

When bases react with acids, what are always produced?

Answer 15

Water and a salt, and sometimes carbon dioxide

Question 16

In precipitation reaction, what is formed?

Answer 16

A solid

Question 17

At room temperature, how much volume does 1 mole of every gas take up?

Answer 17

24 dm^3

Question 18

How do you work out the number of moles of a gas?

Answer 18

Volume in dm^3 / 24dm^3

Question 19

What is the ideal gas equation?

Answer 19

pV = nRT

Question 20

What is the value of R, the gas constant?

Answer 20

8.31 J k-1 mol-1

Question 21

In the ideal gas equation, what is the volume recorded in?

Answer 21

m^3

Question 22

What is a hazard?

Answer 22

Anything that has potential to cause harm or damage

Question 23

What is the risk associated with a hazard?

Answer 23

The probability of someone being harmed if they are exposed to the hazard

Question 24

What is a risk assesement?

Answer 24

Working out how likely it is that something could go wrong, and then thinking of ways to reduce the risk

Question 25

Why do we do titrations?

Answer 25

To work out the amount of an acid i required to neutralise an alkali

Question 26

What is the use of a pipette

Answer 26

To measure the exact volume of a solution

Question 27

What is the use of a burette?

Answer 27

A device which allows you to measure different volumes and add the solution drop by drop

Question 28

Why do you start with a rough titration?

Answer 28

To get an idea of where abouts the end point is

Question 29

What is the titre?

Answer 29

The amount of acid used to neutralise the alkali

Question 30

How long should you repeat the titration for?

Answer 30

Until you get answers that are concordant (similar to each other).

Question 31

What do indicators do?

Answer 31

They change colour very quickly over a small pH change

Question 32

What does the indicator methyl orange do when adding acid to alkali?

Answer 32

Turns yellow to red

Question 33

What does the indicator phenolphthalein do when adding acid to alkali?

Answer 33

It turns red to colourless

Question 34

Why is it best to do a titration on a white surface?

Answer 34

So the colour change is easy to see

Question 35

Why are universal indicators not very useful in titrations?

Answer 35

Because the colour changes gradually over a wide pH range

Question 36

What is the formula of hydroxide?

Answer 36

OH-

Question 37

What is the uncertainty?

Answer 37

The amount of error you might have in a measurement

Question 38

What is the percentage uncertainty?

Answer 38

(Uncertainty / reading ) X 100

Question 39

What is the best way to reduce percentage uncertainty?

Answer 39

Use more precise equipment and use more volume of a liquid

Question 40

What are systematic errors?

Answer 40

Errors caused by the set-up or equipment used

Question 41

What are random errors?

Answer 41

Errors that make the result a little bit different each time

Question 42

What is the best way to deal with random errors?

Answer 42

Repeat the experiment a few times and find a mean value

Question 43

How do you find the total percentage uncertainty?

Answer 43

Add up all the individual uncertainties together

Question 44

What is the percentage?

Answer 44

(actual yield / theoretical yield) X 100

Question 45

What is the atom economy?

Answer 45

A measure of the efficieny of a reaction

Question 46

How do you calculate the atom economy?

Answer 46

( Molar mass of desired product / molar mass of all products ) X 100

Question 47

What is an addition reaction?

Answer 47

A reaction where the reactants form only 1 product