## Pages in this set

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AS TRANSITION COURSE
SUMMER 2012
PART 1: MEASURING AMOUNT OF
SUBSTANCE

MASS VOLUME MOLAR MASS AVOGADRO

CONCENTRATION ATOM ION MOLECULE

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COURSE OUTLINE
OCR Chemistry A
Unit 1 ­ Autumn Term 2012
Atoms and Electron Structure
Moles, Equations and Acids
Structure and Bonding
Redox, Group 2 and Group 7
Unit 1 Exam ­ January 2013 ­ 1 hour ­ 90 UMS ­ 30% of total

Unit 2 ­ Spring Term 2013…

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MEASUREMENTS IN CHEMISTRY

Mass
Convert the following into grams:

a) 0.25 kg
b) 15 kg
c) 100 tonnes
d) 2 tonnes

Volume
Convert the following into dm3:

a) 100 cm3
b) 25 cm3
c) 50 m3
d) 50000 cm3

Tip ­ always use standard form for very large and very…

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What is a mole?
Atoms and molecules are very small ­ far too small to count individually!

It is important to know how much of something we have, but we count particles in MOLES
because you get simpler numbers

1 mole = 6.02 x 1023 particles
(6.02 x 1023 is…

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How can you work out how many moles you have?

a) From a measurement of MASS:
You can find the number of moles of a substance if you are given its mass and you know its
molar mass:

number of moles = mass/molar mass

n = m/mr

Mass MUST be…

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b) From a measurement of AQUEOUS VOLUME:
You can find the number of moles of a substance dissolved in water (aqueous) if you are
given the volume of solution and you know its molar concentration:

number of moles = aqueous volume x molar concentration

n = V x C

Aqueous…

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c) From a measurement of GASEOUS VOLUME:
You can find the number of moles of a gas if you are given the volume of the gas:

number of moles = volume / 24

n = V / 24

24 dm3 is the volume occupied by 1 mole of any gas…