# Amount of Substance

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• Created by: jackjj9
• Created on: 10-10-16 20:54
What is the ideal gas equation?
PV = nRT
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What is the equation to work out the number of moles?
n = mass / Mr
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What is the equation to find concentration?
C = n / volume (in decimetres cubed)
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What must first be found to calculate reacting masses?
The limiting reagent
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What is standard temperature?
273K (0C)
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What is standard pressure?
100kPa
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What volume does 1 mole of gas at rtp occupy?
24dm3
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What volume does one mole of any gas at stp occupy?
22.4dm3
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As temperature increases, does the volume increase or decrease?
Increase
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What is the equation for volume of a gas at rtp?
V = n * 24
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What is the equation for volume of a gas at stp?
V = n * 22.4
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What is theoretical yield?
The maximum amount of product that can be obtained from a reaction, in theory
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Give 2 reasons why actual yield never equals theoretical yield?
Incomplete reactions/unwanted reactions/escaping gasses
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What is a standard solution?
A solution whose concentration is very accurately known
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What is the required practical of this unit?
Titration
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What is the amount added from the burette called?
The titre
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When should you stop repeating a a titration?
When concordant results are found
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What are concordant results?
When 2 results agree to the precision of the apparatus (in the case of a burette, 0.1cm3)
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What is the formula for the efficiency of a reaction?
(Actual yield / Theoretical yield)*100
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What is atom economy?
A way of measuring the amount of wasted/lost atoms in a reaction
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How can you work out atom economy?
(Total Mr of all reactants / Total Mr of all products) *100
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What is empirical formula?
The simplest ratio of all the elements in a compound
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How do you calculate empirical formula from masses?
Assume 100g = 100% and work out number of moles. Divide through by smallest number. Get ratio.
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A compound is found to contain 50.05 % sulfur and 49.95 % oxygen. Empirical formula?
SO2
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How do you calculate the molecular formula from an empirical formula?
Divide the mass given in question by the Mr of the empirical formula and multiply each element by this
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What result should be used in titration calculations?
The average between all the concordant results while ignoring the rough result
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What indicator should be used in a titration?
Phenolphthalein
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What colour is phenolphthalein in an alkali?
Pink
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What colour is phenolphthalein in an acid?
Colourless
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In what molar ratio does a monoprotic acid react?
1:1
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## Other cards in this set

### Card 2

#### Front

What is the equation to work out the number of moles?

n = mass / Mr

### Card 3

#### Front

What is the equation to find concentration?

### Card 4

#### Front

What must first be found to calculate reacting masses?

### Card 5

#### Front

What is standard temperature?