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Unit 2 - Mrs Richards Flashcards

1
Q

Define Molecular mass (Mr)

A

Mass of the atoms in a given formula

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2
Q

Define Avagardo’s Constant

A

It is 6.02 x 10^23. In one mole of ANYTHING, there is always 6.02 x 10^23 of something in it, be it electrons, atoms or molecules.

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3
Q

What is one mole of an element the same as?

A

the Ar in gmol-1

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4
Q

Define empirical formula

A

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

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5
Q

Define Molecular formula

A

The actual number of atoms of each element in a compound

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6
Q

What is the formula of ethanoic acid?

A

CH3COOH

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7
Q

Define atom economy

A

A measure of how much of the products are useful

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8
Q

What type of reaction do we have if the atom economy is 100%

A

An addition reaction

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9
Q

What type of reaction do we have if the atom economy a bit less than 100%

A

A substitution reaction

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10
Q

What type of reaction do we have if the atom economy is a lot less than 100%

A

An elimination reaction

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11
Q

Define an acid

A

They are chemical agents that release hydrogen ions when it is added to water, hydrogen DONATORS

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12
Q

What is the difference between strong and weak acids?

A

Depends on how IONISED it is in water. A strong acid 100% ionised and has a pH of 1, a weak acid is only partly ionised and has a pH of 3-5

SAME FOR ALKALIS (strength depends on how ionised it is)

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13
Q

Define a base

A

A base is a substance that will neutralise an acid, but does not dissolve in water. t is a H+ ion acceptor

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14
Q

Define an alkali

A

It is any substance that produces hydroxide OH- ions when added to water.

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15
Q

Write the ionic equation for the reaction of an acid with any alkali

A

H+ + OH- —> H2O

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16
Q

Name a strong alkali

A

sodium hydroxide solution or calcium hydroxide solution (limewater)

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17
Q

Name a weak alkali

18
Q

How do you complete a titration?

A

See textbook

19
Q

What would the oxidation state of N be?

A

0, as are all elements

20
Q

What would the oxidation state of Fe3+ be?

21
Q

What would the oxidation state of H be in a compound?

A

+1
Only exceptions are - 0 as H or H2
- -1 as a hydride ion, H- and in sodium hydride
NAH

22
Q

What would the oxidation state of O be in a compound?

A

-2
Only exceptions are - 0 as O or O2
- -1 in Hydrogen Peroxide, H2O2
- +2 in F2O

23
Q

What would the oxidation state of F be in a compound?

A

-1

The exception is - as F or F2

24
Q

What must all the oxidation numbers in the compound total?

A

The overall charge of the compound

25
Define Redox
When reduction and oxidation take place
26
If the oxidation state increases, has the element been oxidised or reduced?
Oxidised
27
If the number of electrons has decreased, has the compound being oxidised or reduced?
oxidised, so it will become more positive OILRIG
28
What do we use to balance redox reactions?
electrons, H and H2O
29
How do you combine half equations?
1) Write the out 2) Multiply the equations so that the number of electrons in each is the same 3) Add the 2 equations and cancel out the electrons on either side 4) If necessary, cancel any other species which appear on both sides
30
Define Relative Atomic Mass
The weighted mean mass of an atom of an element compared with 1/12 the mass of carbon -12
31
Define a mole
The amount of any substance that contains the same number of particles as there are carbon atoms in 12g of carbon -12
32
What is the formula for the number of particles present in an atom?
n x (6.02 x 10^23)
33
What is the difference between an atom and a molecule
A molecule is made up of atoms
34
What do we do with percentages when working out empirical formulas?
Treat them as just grams
35
What is 24dm^3 often referred to as?
The molar gas volume
36
What do chemists call strong solutions?
Concentrated
37
What do chemists call weak solutions?
Dilute
38
Define concentration
The number of moles dissolved per dm^3 of solution
39
Why are standard solutions used for titration?
We know the concentration and can use this to work out the moles, hence been able to work out the concentration of the alkali
40
What unit must all values be when dividing by the Mr?
Grams
41
How many grams is 1 tonne
1000000 or 1x10^6

Chemistry (9 decks)

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