C2.3 How Much?
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What number on an atom tells you the RAM
The top one
What is the ram?
Relative atomic mass Protons + neutrons
What number on an atom shows the atomic number and what is the atomic number?
Bottom number Amount of protons
What is the mass a charge of a proton
Mass = 1 Charge = +1
What’s the mass and charge of an electron
Mass = very small Charge = -1
What’s the mass and charge of a neutron
Mass = 1 Charge = 0
What’s an isotope?
Different versions of the same element that have different numbers of neutrons They have a different physical appearance but the same chemical properties
What’s the Mr of H2O? H=1 O=16
(1x2)+(16x1) =18
How do you work out percentage by mass?
Element mass / total RFM (x100)
What’s the equation of moles?
Moles = mass/RAM
What are the steps to calculate the mass of a substance to get the other mass of the substance? Eg. How much hydrogen will I get from 14g of water?
• Use formula triangle to find the moles • Check ratio of the balanced equation • Use formula triangle to calculate mass
What are the steps to find the empirical formula?
% RAM % / RAM Divide by smallest number Make whole number Add numbers into formula
What are advantages of using instrumental methods to analyse substances?
Smaller sample can be used Highly accurate and sensitive Quicker than the traditional methods
What do we use instrumental methods for?
Drug testing Blood tests
What are the steps for gas chromatography?
• Sample is vaporised - heat provided by oven • Sample travels through column, a mixture of compounds is separated by how well it sticks to the column • Separate compounds are detected
What’s a sample?
Mixture of compounds
How do you calculate percentage yield?
Actual mass of product / maximum mass of product
Why do you never get 100% of the product when you extract a gas?
Reversible reaction might not go to completion Some product may be lost when it’s removed from the reaction mixture Some of the reactants may react in an unexpected way