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Chapter 3 - Amount of substance II - Coggle Diagram
Chapter 3 - Amount of substance II
Stiochiometry
The ratio of the amount of each substance in a reaction
Uses
To find quantity of reactants need to produce a certain amount of product
To find the quantities of products that should be formed form certain quantities of reactants
Percentage yield
Theoretical tield - maximum possible amount of product produced in a reaction
Actual yield - amount of substance obtained from a reaction
% yield = actual yield/ theorestical yield
Reasons why % yield isn't 100%
Reaction may not have been completed
Other reactions may have take place alongside the main reaction
Some product may have been lost
Impure reactants
Limiting reagent
Reactant that will be completely used up first and stop the reaction
Can be found by working out the amount of moles of each reactant and comparing them with the equation
Calculations must be based on the limiting reagent
Atom economy
Measure of how well atoms have been utilised
High atom economies
Produce large proportion of desired products and few unwanted waste products
Good for sustainability - best use of natural resources
Assumes 100% yield
Atom economy = molar mass of desired product / molar mass of all products X 100
Improving the atom economy makes industrial process more efficient
Ideal gas equation
Assumptions made about gases
Random motion
Elastic collisions
Negligible size
No intermolecular forces
pV = nRT
Temperature is proportional to average kinetic energy
Ideal gas constant = 8.314 L/k mol
Temperature is in Kelvin, starting at absolute 0 (-273)
Each 1K rise in temperature is the same as a I degree rise in celcius
Experimental techniques
Mass - digital mass balance
Volume - measuring cyliner (if you're making a standard solution, use a volumetric flask
Gas volume - gas syrine, or measure mass lost on a balance