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A Level Chemistry Year 1 > Reactions and Calculations > Flashcards

Reactions and Calculations Flashcards

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1
Q

What are acids also known as?

A

Proton donors

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2
Q

Why are acids also called proton donors?

A

Because when mixed with water, they release Hydrogen ions (as Hydrogen ions have lost an electron, so they’re just a proton)

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3
Q

What are bases also known as?

A

Proton acceptors

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4
Q

Why are bases also called proton accepters?

A

Because they accept Hydrogen ions

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5
Q

What is an alkali?

A

A base that is soluble in water

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6
Q

What do alkalis release in a solution?

A

Hydroxide ions

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7
Q

What is HCl?

A

Hydrochloric Acid

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8
Q

What is H2SO4?

A

Sulfuric Acid

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9
Q

What is HNO3?

A

Nitric Acid

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10
Q

What is CH3COOH?

A

Ethanoic Acid

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11
Q

What is NaOH?

A

Sodium Hydroxide

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12
Q

What is KOH?

A

Potassium Hydroxide

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13
Q

What is NH3?

A

Ammonia

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14
Q

What’s different about the reaction between an acid and water, or a base and water?

A

It’s reversible so both the forwards and backwards reactions will be happening at the same time

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15
Q

What is H3O +?

A

A Hydronium ion (produced when strong acids react fully with water)

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16
Q

What is a strong acid/base?

A

An acid/base that almost completely ionises in water

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17
Q

What is a weak acid/base?

A

An acid/base that only partially ionises in water

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18
Q

Why do strong acids completely ionise in water?

A

Very little of the reverse reaction occurs, meaning nearly all the acid will dissociate (or ionise) in water and so nearly all the H+ ions are released

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19
Q

Why do strong bases completely ionise in water?

A

They favour the forwards reaction, so nearly all the bases dissociates in water and lots of OH- ions are released

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20
Q

Why do weak acids only partially ionise in water?

A

They favour the backwards reaction, and so only a small amount of the acid will dissociate in water and only a few H+ ions are released

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21
Q

Why do weak bases only partially ionise in water?

A

They favour the backwards reaction, and so only a small amount of the base dissociates in water and only a few OH- ions are released

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22
Q

Acid + Base = ?

A

Salt + Water

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23
Q

Metal + Acid = ?

A

Salt + Hydrogen

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24
Q

Metal Oxide + Acid = ?

A

Salt + Water

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25
Metal Hydroxide + Acid = ?
Salt + Water
26
What is a salt?
A compound formed when the Hydrogen in the acid molecule is replaced by a positive ion (metal ion or ammonium ions)
27
What type of reaction is an Acid + Base reaction?
A neutralisation reaction
28
Are Metal Hydroxides normally alkalis or bases?
Alkalis
29
Metal Carbonate + Acid = ?
Salt + Carbon Dioxide + Water
30
What does a solid salt consist of?
A lattice of positive and negative ions (and water in some)
31
What is water of crystallisation?
The water in a lattice
32
What is a hydrated salt?
A salt that contains water of crystallisation
33
What is a anhydrous salt?
A salt that doesn't contain water of crystallisation
34
What are the 5 steps to find the formula of a hydrated salt?
- Find the mass of the water lost (by subtracting the mass of the anhydrous salt away from the mass of the hydrated salt) - Find the number of moles of water lost - Find number of moles of anhydrous salt produced - Work out the ratio of the above - Make the ratio equivalent to 1:n (and then round off n)
35
What are titrations used for?
To find out exactly how much acid is needed to neutralise a quantity of alkali
36
What is the first thing you do when performing a titration?
Do a rough titration
37
Why do you do a rough titration first?
To get an idea where the end point is (where neutralisation occurs)
38
What indicator do you use when doing a titration?
Phenolphthalein (Pink to colourless)
39
What is the titre?
The volume of acid used to neutralise the alkali
40
What is a standard solution?
A solution that has a precisely known concentration
41
What equation links moles, concentration and volume (cm^3)?
Moles = (Concentration x Volume)/1000
42
What equation links moles, concentration and volume (dm^3)?
Moles = Concentration x Volume
43
How do you convert from cm^3 to dm^3?
Divide by 1000
44
What are polyprotic acids?
Acids that donate more than one proton
45
What are 2 categories of polyprotic acids?
``` Diprotic Acids (donate 2 protons e.g. Sulfuric Acid... H2SO4) Triprotic Acids (donate 3 protons e.g. Phosphoric Acid... H3PO4) ```
46
Compared to monoprotic acids, how many times of moles will you need to neutralise a diprotic acid?
2 times as many moles
47
What is theoretical yield?
The mass of product that should be formed in a chemical reaction
48
What does theoretical yield assume?
That no chemicals are lost in the process
49
What are the 3 steps to find theoretical yield?
- Work out how many moles of the limiting reactant you have - Use the chemical equation to work out how many moles of product you would expect that much of reactant to make - Calculate the mass of that many moles of product
50
How does actual yield compare to theoretical yield?
For any reaction, it is always less
51
What are 2 reasons why the actual yield is less than the theoretical yield?
Sometimes not all the 'starting' reactants react fully | Some chemicals are always 'lost' (e.g. lost between transferring between containers)
52
What is percentage yield?
The actual amount of product you collect, written as a percentage of the theoretical mass
53
What equation links percentage yield, actual yield and theoretical yield?
Percentage yield = (Actual yield / Theoretical Yield) x 100
54
What is atom economy?
A measure of the proportion of reactant atoms that become part of the desired product in the balanced chemical equation
55
What equation links % atom economy, molecular mass of desired product and sum of molecular masses of all products?
% atom economy = (Molecular mass of desired product / Sum of molecular masses of all products) x 100
56
What happens in an addition reaction?
The reactants combine to form a single product
57
What is the atom economy (as a %) for an addition reaction?
100%, since no atoms are wasted
58
What happens in a substitution reaction?
Some atoms from one reactant are swapped with atoms from another reactant
59
What does a substitution reaction form?
2 products - the desired product and at least one by-product
60
What is the atom economy (as a %) for a substitution reaction?
Always less than 100%
61
What does it mean if something is sustainable?
It can occur over a long period of time, without damaging the environment or depleting limited natural sources
62
What does a low atom economy cause?
A large amount of waste to be produced
63
What is the oxidation number (oxidation state) of an element?
The total number of electrons it has donated or accepted to form an ion or part of a compound
64
What is the oxidation number of uncombined elements (and elements bonded to identical elements)?
0 - As they haven't accepted or donated any electrons
65
What is the oxidation number of a simple monatomic ion?
The same as it's charge
66
How do you find the oxidation number of molecular ions?
Sum all of the oxidation numbers of all the atoms in the molecule
67
What is the sum of the oxidation numbers in a neutral compound equal to?
0
68
What are the 2 exceptions for the oxidation numbers of oxygen?
``` When in peroxides = -1 Molecular oxygen (O2) = 0 ```
69
What are the 2 exceptions for the oxidation numbers of Hydrogen?
``` When in metal hydrides = -1 Molecular Hydrogen (H2) = 0 ```
70
How do you write an element that has different oxidation numbers?
With Roman Numerals e.g. (I) = +1
71
What is a loss of electrons called?
Oxidation
72
What is a gain of electrons called?
Reduction
73
What is a redox reaction?
A reaction where oxidation and reduction occurs simultaneously
74
What is an oxidising agent?
Something that accepts electrons and get's reduced
75
What is a reducing agent?
Something that donates electrons and get's oxidised
76
When an element is reduced, it's oxidation number is reduced
:)
77
Give an example of a redox reaction
When metals react with acids

A Level Chemistry Year 1 (9 decks)

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