# Amount of substance

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• Created by: ZoeKing98
• Created on: 04-05-16 22:51
Define relative atomic mass
the ratio of the average mass of one atom of an element relative to one twelfth of the mass of an atom of carbon-12.
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Define molecular mass
the ratio of the average mass of one molecule of an element or compound relative to one twelfth of the mass of an atom of carbon-12.
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What type of relative mass do ionic compounds hold?
relative formula mass
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6.022x10^23
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The number of atoms in 1 mole (12g) of carbon-12
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What is the formula to work out the number of moles of a substance?
Mass(g)/mass of one mole(g)
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What is a solution?
A solvent with a solute dissolved in it
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What does the concentration of a solution tell us?
How much solute is present in a known volume of solution
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What are concentrations of solutions measured in?
moldm^-3 (eg 1moldm^-3 means there is 1 mole of solute per cubic decimetre)
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What is the formula to work out number of moles in solution?
concentration (moldm^-3)
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State the ideal gas equation
PV=nRT
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What must volume be expressed in?
m^3
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What must temperature be expressed in?
Kelvin
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How do you convert from Celcius to Kelvin?
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What does R stand for?
Gas constant
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What is empircal formula?
The simplest whole number ratio of atoms within a molecule or compound
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What is molecular formula?
The actual number of atoms of each element in one molecule of the compound
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What are ionic equations?
The equation of changing ions within a reaction
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What are spectator ions?
Ions that do not take part in a reaction
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What is atom economy?
The efficiency of a chemical reaction found by comparing the total number of atoms in the product witht the total number of atoms in the starting materials (in theory, how many atoms must be wasted and used in a reaction)
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What is the equation for atom economy?
(Mass of desired product/total mass of reactants) x 100
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State one way you can improve atom economy
Forming a single desirable reactant
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What is percentage yield?
The actual amount of product produced divided by the theoretical amount expressed as a percentage
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What is the equation for percentage yield?
(The actual number of moles of a specified product/theoretical maximum number of moles of the product) x 100%
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State why percentage yield may not be 100%
- reversible reactions - loss of product through: evaporation, filtering, transferral - not all reactants react
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## Other cards in this set

### Card 2

#### Front

Define molecular mass

#### Back

the ratio of the average mass of one molecule of an element or compound relative to one twelfth of the mass of an atom of carbon-12.

### Card 3

#### Front

What type of relative mass do ionic compounds hold?