Chapter 5 Flashcards

1
Q

How many particles are there in 1 mole?

A

6.02 x 10^23

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2
Q

What is Avagadro’s constant?

A

The number of particles in 1 mole

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3
Q

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

A

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

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4
Q

What is the molar mass?

A

The mass per mole of something

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5
Q

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

A

Yes

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6
Q

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

A

Moles = mass of substance / molar mass of substance

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7
Q

What is the equation for moles in terms of concentration?

A

Moles = concentration x volume

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8
Q

What is concentration usually measured in?

A

Moles / dm^3

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9
Q

What does the empirical formula give you?

A

The smallest whole number ratio of atoms

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10
Q

What does the molecular formula give you?

A

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

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11
Q

What is the percentage composition of an element?

A

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

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12
Q

What do ionic equations show?

A

The reacting particles only

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13
Q

How do you work through an ionic eqution?

A

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

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14
Q

What happens in a displacement reaction?

A

On element replaces another

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15
Q

When bases react with acids, what are always produced?

A

Water and a salt, and sometimes carbon dioxide

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16
Q

In precipitation reaction, what is formed?

A

A solid

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17
Q

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

A

24 dm^3

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18
Q

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

A

Volume in dm^3 / 24dm^3

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19
Q

What is the ideal gas equation?

A

pV = nRT

20
Q

What is the value of R, the gas constant?

A

8.31 J k-1 mol-1

21
Q

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

A

m^3

22
Q

What is a hazard?

A

Anything that has potential to cause harm or damage

23
Q

What is the risk associated with a hazard?

A

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

24
Q

What is a risk assesement?

A

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

25
Q

Why do we do titrations?

A

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

26
Q

What is the use of a pipette

A

To measure the exact volume of a solution

27
Q

What is the use of a burette?

A

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

28
Q

Why do you start with a rough titration?

A

To get an idea of where abouts the end point is

29
Q

What is the titre?

A

The amount of acid used to neutralise the alkali

30
Q

How long should you repeat the titration for?

A

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

31
Q

What do indicators do?

A

They change colour very quickly over a small pH change

32
Q

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

A

Turns yellow to red

33
Q

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

A

It turns red to colourless

34
Q

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

A

So the colour change is easy to see

35
Q

Why are universal indicators not very useful in titrations?

A

Because the colour changes gradually over a wide pH range

36
Q

What is the formula of hydroxide?

A

OH-

37
Q

What is the uncertainty?

A

The amount of error you might have in a measurement

38
Q

What is the percentage uncertainty?

A

(Uncertainty / reading ) X 100

39
Q

What is the best way to reduce percentage uncertainty?

A

Use more precise equipment and use more volume of a liquid

40
Q

What are systematic errors?

A

Errors caused by the set-up or equipment used

41
Q

What are random errors?

A

Errors that make the result a little bit different each time

42
Q

What is the best way to deal with random errors?

A

Repeat the experiment a few times and find a mean value

43
Q

How do you find the total percentage uncertainty?

A

Add up all the individual uncertainties together

44
Q

What is the percentage?

A

(actual yield / theoretical yield) X 100

45
Q

What is the atom economy?

A

A measure of the efficieny of a reaction

46
Q

How do you calculate the atom economy?

A

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

47
Q

What is an addition reaction?

A

A reaction where the reactants form only 1 product