Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Chemistry > Amount Of Substance > Flashcards

Amount Of Substance Flashcards

(72 cards)

Start Studying
1
Q

How do you calculate relative molecular mass?

A

Add together the relative atomic masses of each atom present in a molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do you calculate the number of moles?

A

Number of moles= mass/ molecules mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What must mass always be in?

A

Grams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do you calculate the number of particles of something?

A

Number of particles= Avogadro number x number of moles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does one mole of an element contain?

A

6.022 x10^23 atoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does one mole of a substance contain?

A

The same number of atoms as another mole of a substance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the relative molecular mass of a substance?

A

The mass in grams of on mole of that molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the steps to working out rafting masses?

A

Calculate the moles of the known reactant or product
Multiply or divide the number of moles according to the ratio
Calculate the mass required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define concentration

A

Amount of a compound present in a set volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In what 3 ways can concentration be expressed?

A

Grams per decimetre
Grams per litre
Moles per litre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do you convert centimetres cubed to decimetres cubed?

A

Divide by 1000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do you calculate the the number of moles in a solution?

A

Number of moles= volume x concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do you convert moles to grams?

A

Number of moles= mass/ mr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do you calculate the concentration of a solution?

A

Concentration = number of moles / volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do you calculate the volume of a solution?

A

Volume = number of moles/ concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What value does Avogadro constant have?

A

6.022 x 10^23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a mole?

A

A specific number of particles
6.022 x10^23 particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the relative atomic mass of an atom?

A

The sum of protons and neutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are some useful conversions to know?

A

1 centimetre cubed= 1 ml
1 decimetre cubed= 1 litre
1000 centimetres cubed = 1 decimetre cubed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is standard temperature known as?

A

25 degrees Celsius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is standard pressure?

A

100 kPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

With both standard temperature and pressure what happens to a gas?

A

One mole of gas occupies 24 decimetres cubed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is standard temperature in kelvin?

A

295 k

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do you calculate the number of moles in a gas?

A

Moles= volume/ 24
All in decimetres cubed
This only works if you have standard temperature and pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
When can the ideal gas equation be used?
With any temperature and pressure
26
What value does the gas constant hold?
8.31
27
What is the ideal gas equation?
pV= nRT
28
How do you calculate the mass of a substance?
Mass = moles x mr
29
What is the conservation of mass?
Mass of the reactants= mass of the products
30
What is stoichometry?
The ratio of reactants and products in a chemical reaction. Ratio is important when trying to predict the amount of products in a reaction or the amount of reactants required
31
When does a chemical reaction finish?
When one of the reagents is used up
32
What is the mole used to measure?
The quantities of different substances
33
What is a limiting reagent?
The reagent theta is used up first It causes the chemical reaction to stop
34
How do you calculate the limiting reagent?
Calculate moles of all reactants Compare ratio of all reactants Identify the reagent used up first
35
What equipment is used when measuring a liquid?
Measuring cylinder Burette Volumetric flask
36
State the correct units when using the ideal gas equation
Pressure = Pa - pascals Volume= metres cubed Moles= mole Temperature= kelvin
37
What do each of the letters in the ideal gas equation mean?
P= pressure V= volume n= moles R= ideal gas constant T= temperature
38
How do you answer a question using the ideal gas equation?
Convert all values to correct units Re arrange equation to get correct subject Add in values and solve the equation
39
State some important unit conversions when using the ideal gas equation
KPa to Pa= x1000 Degrees Celsius to kelvin= +273 Centimetres cubed to metres cubed= divide by 10^6 Decimetres cubed to metres cubed= divide by 1000
40
What is empirical formula?
The simplest ratio of atoms of each element in a compound
41
What is molecular formula?
The total number of atoms of each element present in a molecule of the compound
42
How do you calculate the molecular formula?
Calculate mass of empirical formula Divide molecular mass by empirical mass Multiply the atoms present in the empirical formula
43
What is percentage composition?
The amount of an element in a compound is represented as a percentage of the overall compound
44
What is the equation for percentage composition?
Percentage composition= mass of element/ mass of compound x 100
45
What is percentage yield?
A comparison between how much you could make in theory compared with how much you actually did make
46
What does a higher yield mean?
That there is more product to sell which is important in industry
47
What is the equation for percentage yield?
Percentage yield= actual/ theoretical x100
48
What should your answer be less than?
100% If it’s not then your answer is wrong
49
What is atom economy?
How much useful product is produced compared to the mass of the reactants
50
What is the equation for atom economy?
Atom economy = useful product/ total reactants x100
51
What happens if atom economy is decreased?
More products are produced
52
What happens if atom economy is increased?
Less products are produced
53
What is the equation for percentage purity?
Percentage purity = mass of pure sample / mass of impure sample x 100
54
What is a titration?
Measuring how many moles of a known solution is required to neutralise an unknown concentration of solution
55
What are concordant results?
Results from the titration within 0.1 centimetres cubed of each other Repeat until you obtain this
56
What is a back titration?
When a compound is reacted with an excess of acid or base First react acid or base in excess with an unknown Calculate remaining acid or base using a titration Moles of unreacted acid/ base determined by titration Use this information to calculate how much of the unknown we had
57
What is the equation for percentage purity?
Percentage purity= mass of pure sample/ total mass of sample x 100
58
How do you carry out a back titration calculation?
Calculate the moles of unreacted HCl using the titration data given in the question Calculate the moles of reacted HCl by working out the number of moles we started with and the number of moles we have remaining Calculate the moles of the base by looking at the reaction stoichometry Calculate the percentage purity of he sample
59
What is a neutralisation reaction?
It occurs when an acid reacts with an alkali r base to produce salt and water
60
What do titrations determine?
The concentration of an unknown solution
61
What are the 5 steps to a titration?
A known concentration of acid can be reacted with an unknown concentration of base The volume required to neutralise the acid is recorded 3 concord ant results are required. The number of moles of the acid can be calculated Using the equation for the reaction we can determine the number of moles of base present Knowing the volume means we can work back to find the concentration of the base
62
What is a titre?
The difference between the final and initial readings on a burette You do not have to set it back to zero each time The rough titre is first to see whereabouts roughly how much it takes
63
How is acid added?
Slowly from a burette until the indicator changes colour
64
How is the burette prepared ?
It is washed out with distilled water and then solution It’s accurate to 0.05 centimetres cubed So the uncertainty is 0.10 Read the bottom of the meniscus at eye level
65
How is the pipette prepared?
Used to measure the solution going into the conical flask Washed out with the solution Accuracy varies but about 0.01 Meniscus lies above graduated line and not level with it
66
What role does the conical flask have?
Not used to measure anything Don’t use it to take any readings Can be washed out with distilled water but doesn’t need to be left to dry Most in accurate piece of equipment
67
What is the conical flask placed on?
A white tile so the colour change can be seen more clearly
68
What is ignored when gathering concord at results?
The rough titre Do not use it
69
State two examples of indicators
Methyl orange for a strong acid like hydrochloric Phenolphthalein for a strong alkali like sodium hydroxide
70
How does phenolphthalein change colour?
Colourless in an acid Pink in a base
71
How does methyl orange change colour?
Red in an acid Yellow in a base
72
What happens when an ionic substance dissolves in water?
The positive and negative ions separate and become hydrated They interact with the water molecules rather than each other Some ions may nit be involved in this reaction and so are called spectator ions

Chemistry (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions