# C2 How much?

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• Created by: KAustria
• Created on: 10-05-14 08:09
What is the relative mass of a proton and neutron?
1
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What is the mass number?
Proton and Neutron
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What is the atomic number?
Proton (and electron)
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What are isotopes?
Atoms of the same element but with different number of neutrons
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What is the relative atomic mass of an element?
The average value for the isotopes of the element
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How do you work out the relative formula mass (Mr)?
By adding up all of the Ar
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When would we use moles?
When we need to work out how much of a substance reacts to how much product we will get.
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The relative formula mass of a substance in grams is called what?
one mole of that substance
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If you wanted to find out how much of an element made up a compound, what formula would you use?
Ar / Mr x 100 = %
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How do you work out the emprical formula of a compound?
1. Divide mass of substance by its Ar 2. Divide the ratios given by the smallest value
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How do you calculate masses from chemical equations?
1. Balance the equation 2. Add up the Ar of the elements you are interested in 3. Divide to get one 4. Multiply to get the number you are looking for.
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How do you calculate the percentage yield?
% yield= actual yield / predicted yield x 100
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Why can you never get 100% yield?
Yield can be lost because of incomplete reactions, lost when it its separated, lost when collected from apparatus.
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What is a reversible reaction?
When the products of of a chemical reaction can react together to create the original reactants
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Describe chromotography
1. A spot of colour is put onto paper 2. Solvent is allowed to move through the paper 3. The colours move different distances depending on their solubility.
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What method would you use to find identify elements (separate) in a compound and their mass?
gas chromotography and a mass spectrometer.
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Give the step-by step process of gas chromotography?
1. Mixture is carried by gas through a long column pact with solid particles 2. Compounds travel at different sperds through the column 3. The amount of substances leaving against time shows number of compounds and retention time.
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How can you use retention times?
Compare the results with known compounds to help identify what compounds are in the mixture.
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What is the main purpose of the gas chromatography column in GC - MS analysis?
To separate the compounds n the mixture
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What is the function of a mass spectrometer?
Gives the relative molecular mass of a compound.
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What is the molecular ion peak?
It is furthest to the right o the spectrum and shows the relative molecular mass of the compound.
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## Other cards in this set

### Card 2

#### Front

What is the mass number?

#### Back

Proton and Neutron

### Card 3

#### Front

What is the atomic number?

### Card 4

#### Front

What are isotopes?

### Card 5

#### Front

What is the relative atomic mass of an element?