OCR Chemistry Mod 1 Flashcards

Including moles, empirical formula, Relative atomic mass, Titration calculations and more

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  • Created by: Ellie
  • Created on: 06-11-13 17:09
Define a Molecule
A group of atoms held together by a covalent bond
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What is the molecular formula?
The actual number of atoms of each element in a molecule
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Define Relative Atomic Mass
It is the weighted mean mass of an atom of an element compared with carbon 12 which is 12
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Define Relative Isotopic Mass
It is the mass of an atom of an isotope compared to the mass of Carbon-12 which is 12
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Define an isotope
Isotopes are atoms of the same element with different numbers of neutrons
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Define atomic number
The number of protons in the nucleus of an atom
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Define mass/nucleon number
The number of particles in the nucleus
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What is Molar Mass?
Molar mass - units:gmol-1 - is mass per mole of a substance
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What is empirical formula?
The simplest whole number ratio of atoms of each element present in a compound
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What is the relative of protons and neutrons?
1
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What is the relative mass of an electron?
1/2000
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What is an ion?
Positively or negatively charged atoms or covalently bonded group of atoms
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How do you work out Relative Atomic Mass?
Ar = (isotope1% / 100 x Isotope number) + (isotope2% / 100 x isotopic number)
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Define Avogadro constant
The number of atoms per mole of the C-12 isotope (or 6.02x10 23)
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Define Mole
The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the C-12 isotope
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How do you find the mass of 1 mol of atoms of any element?
Relative atomic mass in grams
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How do you find Molar Mass?
Add together all the relative Ars for each atom in a formula
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Equation for amount of substance or moles?
Moles = mass/Mr
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Steps to Calculate Empirical Forumula
1. Find molar ratio of atoms 2. Divide each side by smallest number to get 1 3. Write numbers in formula
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What is molar volume, its unit and its value at room temperature?
The volume per mole of a gas. Units are dm3mol-1 and at room temperature and pressure the molar value is approx 24.0 dm3mol-1
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What is the equation to work out molar volume?
moles = volume / 24
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What is the equation to find the concentration of a solution?
Concentration = Moles / Volume
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What is the unit for concentration?
moldm-3
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Steps of a titration calculation
1. Find moles of known. 2.Balanced equation = ratio 3.Find moles of unknown
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How do you calculate % yield?
actual yield/ theoretical yield x 100%
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Reasons why % yield is not 100%
Not all product recovered, reactant impurities, a side reaction occurs and reaction does not reach completion
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Other cards in this set

Card 2

Front

What is the molecular formula?

Back

The actual number of atoms of each element in a molecule

Card 3

Front

Define Relative Atomic Mass

Back

Preview of the front of card 3

Card 4

Front

Define Relative Isotopic Mass

Back

Preview of the front of card 4

Card 5

Front

Define an isotope

Back

Preview of the front of card 5
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