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CHEMISTRY F321 - Atoms, Bonds and Groups: 1.1 Moles, Equations and Acids
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Amount of substance
The quantity of substance, expressed in a unit called the mole. This measures a number of particles.
Avagadro's constant
The number of particles in a mole: 6.02 x 10
23
What does a mole measure?
An amount of substance/particles/molecules/atoms
what is the unit for molar mass?
gmol
-1
Molar mass
The mass of one mole of substance (Mr)
Empirical formula
The lowest whole number ration of atoms of each element in a compound
Molecular formula
The actual number of atoms of each element in a molecule
4 steps to calculate empirical formula
1. Calculate moles (or mole percentages)
2. Calculate the lowest ratio (by dividing by the smallest)
3. Make them all whole numbers
4. State the formula
How do you determine the molecular formula from the empirical formula?
Take the given molar mass and DIVIDE by the empirical formula mass (using your EF)
Find moles, involving mass.
Moles = Mass / Mr
Find moles, involving gas volume.
Moles = Volume / 24
Find moles, involving solution volume and concentration.
Moles = Volume x Concentration
How can number of moles be deduced from a previously balanced equation?
Using ratios
What can we use to determine ratio in the formulae of a compound?
Its valency
Valency can tell us what about the atom...
Which group it is in (in the periodic table)
The -ate suffix tells us...
the ion contains oxygen and is negatively charged
Definition of a mole
6.02 x 10
23
particles
Acid
Releases H
+
ions in solution. (Proton donor)
Formula for hydrochloric acid
HCl
Formulae for sulphuric acid
H
2
SO
4
Formulae for nitric acid
HNO
3
Base
Proton acceptor
Alkali
A soluble base that releases OH
-
ions in solution
Salt
When the H
+
ion of an acid is replaced by a metal ion or NH
4
+
What is OBSERVED when acids react with a metal oxide?
Solid disappears
What is OBSERVED when an acid reacts with metal carbonates?
Solid disappears and bubbles are seen
What is OBSERVED when an acid reacts with an alkali?
There is NO observable change
Anhydrous
The compound that remains when the water of crystallisation is removed from a hydrated salt.
Hydrated
A complex compound which has water molecules incorporated
Water of Crystallisation
Water molecules which make up part of the crystal structure of a compound (easily removed by heating)
List the 4 steps to determine the formula of a hydrated salt
1. Calculate the mass of water (mass of hydrated - mass of anhydrous)
2. Calcualte moles of anhydrous and moles of water
3. Calculate the mole ratio between the anhydrous and the water
4. State the formula of the hydrated salt
Author
jpopat
ID
181321
Card Set
CHEMISTRY F321 - Atoms, Bonds and Groups: 1.1 Moles, Equations and Acids
Description
1.1 Moles, Equations and Acids
Updated
2012-12-23T14:32:35Z
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