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19 Cards in this Set
- Front
- Back
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What is an isotope?
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An atom with the same atomic number as another but with a different mass number.
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Why do isotopes have the same chemical properties?
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They have the same electronic structure.
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What is the RAM or Ar?
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The weighted average mass of an element. Itt is measurement on a scale which the carbon-12 atom has a mass of exactly 12 units.
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What is a mole?
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A measure of amount of substance.
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What is the Avogadro number?
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The number of atoms in 12g of carbon-12. It is about 6.02 x10 [23]
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How do you calculate the RAM of an element using the relative abundances of its isotopes? (3)
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Multiply each % with its relative mass
Add them all together and divide by 100 This gives you a weighted average of the RAM |
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Moles =
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Mass/RAM
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Describe how to obtain the formulae of simple compounds experimentally.
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Find mass of each element
Divide each by its RAM Divide both by the smallest to give ratio |
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What is water of crystallization?
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The water associated with a salt when it is a hydrated solid
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How do you indicate the number of moles of water of crystallization?
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A dot followed by a number and the formula for water
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What is the empirical formula?
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It is the simplest formula made up from the ratio of the elements
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How do you find the molecular formula from the molecular mass?
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Take the empirical formula
Find the empirical formula mass Divide the molecular mass by the empirical formula mass Take this to be 'n' Multiply the empirical formula by 'n' |
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How do you deduce the masses of reactants needed and the mass of product formed?
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The total mass of starting materials will be equal to the mass of the products.
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Moles of a gas =
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Volume/24,000
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One mole of any gas occupies ....
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24dm(3) at rtp
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1dm = ...cm
1cm(3) = ... cm(3) |
1dm = 10cm
1cm(3) = 1000cm(3) |
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Moles of a solution =
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Concentration x volume
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Unit of concentration is
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moles per decimeter cubed
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How do you calculate the % yield?
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Actual yield/expected yield x 100
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