Topic 5-formulae, Equations And Amount Of Substances

Question 1

What is a mole.

Answer 1

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Question 2

be able to use the Avogadro constant, L, (6.02 × 1023 mol-1) in calculations

Answer 2

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Question 3

know that the molar mass of a substance is the mass per mole of the substance in g mol-1

Answer 3

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Question 4

know what is meant by the terms ‘empirical formula’ and ‘molecular formula’

Answer 4

Empirical formula-

Molecular formula-

Question 5

be able to use experimental data to calculate
i. empiricalformulae
ii. molecular formulae including the use of pV = nRT for gases and volatile liquids
Calculations of empirical formula may involve composition by mass or percentage composition by mass data.

Answer 5

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Question 6

be able to write balanced full and ionic equations, including state symbols, for chemical reactions

Answer 6

Tailoired rurours

Question 7

be able to calculate amounts of substances (in mol) in reactions involving mass, volume of gas, volume of solution and concentration
These calculations may involve reactants and/or products.

Answer 7

Triangles

Question 8

be able to calculate reacting masses from chemical equations, and vice versa, using the concepts of amount of substance and molar mass

Answer 8

Tt

Question 9

be able to calculate reacting volumes of gases from chemical equations, and vice versa, using the concepts of amount of substance

Answer 9

Tt

Question 10

be able to calculate reacting volumes of gases from chemical equations, and vice versa, using the concepts of molar volume of gases

Answer 10

Tt

Question 11

be able to calculate solution concentrations, in mol dm-3 and g dm-3, including simple acid-base titrations using a range of acids, alkalis and indicators
The use of both phenolphthalein and methyl orange as indicators will be expecte

Answer 11

Tt

Question 12

be able to:
i calculate measurement uncertainties and measurement errors in experimental results
ii comment on sources of error in experimental procedures

Answer 12

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Question 13

understand how to minimise the percentage error and percentage uncertainty in experiments involving measurements

Answer 13

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Question 14

be able to calculate percentage yields and percentage atom economies using chemical equations and experimental results
Atom economy of a reaction= molar mass of the desired product ×100% sum of the molar masses of all products

Answer 14

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Question 15

be able to relate ionic and full equations, with state symbols, to observations from simple test tube reactions, to include:
i displacement reactions
ii reactions of acids
iii precipitation reactions

Answer 15

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Question 16

understand risks and hazards in practical procedures and suggest appropriate precautions where necessary

Answer 16

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Question 17

What are the three core practicals in topic 5

Answer 17

CORE PRACTICAL 1: Measure the molar volume of a gas

CORE PRACTICAL 2: Prepare a standard solution from a solid acid and use it’s find the concentration of a solution of sodium hydroxide

CORE PRACTICAL 3: Find the concentration of a solution of hydrochloric acid