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Chemistry OCR A Level > Module 2.1 > Flashcards

Module 2.1 Flashcards

1
Q

Define the term isotope

A

Atoms of the same element with a different number of neutrons and different masses

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2
Q

Why are the reactions of isotopes the same?

A

Chemical reactions only involve electrons. Isotopes have the same number of electrons. Therefore, they have the same chemical reaction

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3
Q

What is the relative mass and relative charge of a proton, neutron and electron

A

Proton

Relative mass = 1
Relative charge = 1

Neutron

Relative mass = 1
Relative charge = 0

Neutron

Relative mass = 1/2000
Relative charge = -1

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4
Q

What never changes? The number of neutrons, the number of protons or the number of electrons?

A

Number of protons

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5
Q

In the diagram of an atom, where are the electrons?

A

In orbitals

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6
Q

In the diagram of an atom, where is the nucleus and what is inside it?

A

Location - Within the first outer orbital

Inside - Protons and Neutrons

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7
Q

Define relative isotopic mass

A

Mass of an isotope compared with 1/12th mass of an atom of carbon-12

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8
Q

Define relative atomic mass

A

Weight mean mass of an atom compared with 1/12th mass of an atom of carbon-12

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9
Q

How do you find the Mr of an element?

A

1) Multiply each relative isotopic mass by its relative isotope abundance and then add the result
2) Divide this result by the sum of the isotope abundances

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10
Q

When do we use the term relative molecular mass?

A

When referring to simple molecules

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11
Q

When do we use the term relative formula mass?

A

When we are referring to ionic or giant covalent molecules

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12
Q

List the ions formed by Group 1 - 7 elements (excluding group 4)

A

Group 1 = 1+
Group 2 = 2+
Group 3 = 3+

Group 5 = 3-
Group 6 = 2-
Group 7 = 1-

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13
Q

What should we do when trying to work out the formula for ionic compounds?

A

Balance out the charges

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14
Q

What are the names of the following ions?

NO3 ^ -
CO3 ^ 2-
SO4 ^ 2-
OH ^ - 
NH4 ^ +
Zn ^ 2+
Ag ^ +
A 
Nitrate ion
Carbonate ion
Sulfate ion
Hydroxide ion
Ammonium ion
Zinc ion
Silver ion
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15
Q

Define amount of substance

A

INSERT EXAM Q DEFINITION HERE

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16
Q

Given mass and Mr, what is the formula for moles?

A

n = m/Mr

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17
Q

Given moles and Mr, what is the formula for mass?

A

m = n x Mr

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18
Q

Given moles and mass, what is the formula for Mr?

A

Mr = m/n

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19
Q

What is the formula for Number of particles?

A

n x Avogadro’s constant

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20
Q

Given Avogadro’s constant and the number of particles, what is the formula for moles?

A

Np/ Avogadro’s constant

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21
Q

Define empirical formula

A

The simplest whole number ratio of atoms of each element present in a compound

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22
Q

How do work out the empirical formula of a compound starting from its percentage composition?

A

1) Divide each percentage by its atomic mass
2) Divide each answer by whichever answer is the smallest
3) Find the Lowest whole number ratio

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23
Q

How do you work out the empirical formula of a compound starting from its mass composition?

A

1) Divide each amount of grams by its atomic mass
2) Divide each answer by whichever answer is the smallest
3) Find the Lowest whole number ratio

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24
Q

What does anhydrous mean?

A

Without water

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25
What does hydrated mean?
Structure consists of water
26
Define water of crystallisation
Water molecules that from an essential part of the crystalline structure of a compound
27
How do you find the water of crystallisation of a compound?
1) Work out the anhydrous mass 2) Calculate the amount of anhydrous salt (in moles) 3) Calculate the amount of water (in moles) 4) Divide the the smallest number 5) Find the lowest whole number ratio
28
For a gas at RTP, what formula would you use to work out the volume in cm^3
v = n x 24000
29
For a gas at RTP, what formula would you use to work out the volume in dm^3
v = n x 24
30
Given the concentration and volume, how can you find the number of moles?
n = C x V
31
Given the moles and volume, how can you find the concentration?
C = n/V
32
Given the moles and concentration, how can you find the volume?
V = n/C
33
What is the ideal gas equation?
pV = nRT
34
What do the units stand for in the ideal gas equation?
``` p = Pressure (Pa) V = Volume (m^3) n = moles (mol) R = The Gas Constant T - Temperature (K) ```
35
How do you convert Pascals to Atmospheres?
1 atm = 101325 Pa
36
How do you convert Degrees Celsius to Kelvin?
+273
37
How do you convert dm^3 / Litres to m^3
Divide by 1000
38
What is the formula for percentage yield?
(Actual yield/Theoretical Yield ) x 100
39
Define percentage yield
A measurement of the efficiency of a reaction. It is the ratio between the actual yield and theoretical yield.
40
Define theoretical yield
The amount of the product that should be made if no chemicals are 'lost' in the process
41
Define actual yield
The amount of product actually obtained from a chemical reaction
42
Why will the actual yield never be 100%?
- The reaction may be at equilibrium and may not reach equilibrium - Side reactions may occur leading to the formation of by-products - The reactants may not be pure. - Some of the reactants may be left behind in the apparatus used in the experiment
43
What steps do you use to find percentage yield?
1) Write a balanced equation 2) Find the mole ratio 3) Find the theoretical yield 4) Calculate the percentage yield using the formula
44
Define atom economy
The amount of starting materials, that end up as useful products
45
What is the formula for atom economy?
Mr of useful products / Total Mr of reactants
46
What type of reaction has an atom economy of 100%?
Addition reactions
47
What type of reactions do not have an atom economy of 100%?
Any reaction that is not an addition reaction
48
Name the following acids: HCl, H2SO4, HNO3 and CH3COOH
HCl - Hydrochloric acid H2SO4 - Sulphuric acid HNO3 - Nitric acid CH3COOH - Ethanoic acid
49
Name the following alkalis: NH3, KOH and NaOH
NH3 - Ammonia KOH - Potassium Hydroxide NaOH - Sodium Hydroxide
50
Define the term acid
Proton donor
51
Define the term alkali
Proton acceptor
52
What do acids release in aq solutions?
Protons (H+)
53
What do alkalis release in aq solution?
Hydroxide ions (OH-)
54
Show the dissociation of HCl, HNO3 and H2SO4
HCl → H+ + Cl- HNO3 → H+ + NO3- H2SO4 → 2H+ + SO4 ^2- NOTE : All reactants and products should be in aq solution
55
Show the reaction between water and ammonia
NH3(aq) + H2O (l) → OH- + NH4+
56
Show the reaction between a proton and a hydroxide ion
OH- + H+ → H2O
57
Define the term salt
When the H+ ion(s) in an acid is replaced by metal ions
58
What are the products in the reaction between an acid and a metal?
Salt + Hydrogen
59
What are the products in the reaction between an acid and a metal hydroxide?
Salt + Water
60
What are the products in the reaction between an acid and metal oxide?
Salt + Water
61
What are the products in the reaction between an acid and a metal carbonate?
Salt + CO2 + Water
62
What is meant by a titration?
A technique used to determine the concentration of a solution
63
Outline the method of a titration
- Add acid to burette and record the initial volume - Measure alkali in volumetric pipette using a pipette filler and add this to a conical flask - Add a few drops of indicator - Add the acid slowly to the concial flask until there is a colour change - Record the final volume of the burette - From this, calculate the volume added
64
How can we make a standard solution?
- Weigh a specific mass of a ample - Add a small volume of distilled water and stir until the solid has dissolved - Transfer solution into a volumetric flask using a funnel - Rinse the breaker and funnel into the volumetric flask using distilled water so no reactants are left behind. - Add water wisely until the volume equals the white mark on the volumetric flak - Shake and invert the flask to mix the contents.
65
When performing titration calculations, what are the key things you must do?
- Convert volume to right unit (if necessary) - Find the mole ratio - Use stoichiometric relationships
66
How do you work out titration calculation answers?
1) Balance the equation and find the mole ratio 2) Find the number of moles of titrant added to reach the end point 3) Determine the amount of moles of analyte that must have been present 4) Determine the concentration of the analyte 5) Check answer and check units
67
All elements by them-self has an oxidation number of :
0 e.g. He
68
The oxidation states of any molecules adds up to :
0 e.g. MgO
69
The oxidation state of any ion is equal to?
The charge of that ion e.g. Mg^2+ has an oxidation state of 2+
70
Any group 1 element has an oxidation state of?
1+
71
Any group 2 element has an oxidation state of?
2+
72
Any group 3 element has an oxidation state of?
3+
73
The oxidation state of Fluorine is always?
-1
74
The oxidation state of Hydrogen is nearly always?
+1 Except for when in Metal Hydrides e.g. NaH, where it is -1
75
The oxidation state of oxygen is?
Nearly always -2 Except IN F2O and peroxides
76
The oxidation state of chlorine is nearly always?
-1 Except when bonded to oxygen
77
In terms of oxidation number, what is oxidation?
An increase in oxidation number
78
In terms of oxidation number, what is reduction?
An decrease in oxidation number
79
In terms of electrons, what is oxidation?
A loss in electrons
80
In terms of oxidation number, what is reduction?
A gain of electrons

Chemistry OCR A Level (15 decks)

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