Formulae and amounts of substance Flashcards
What is the empirical formula?
The simplest whole number ratio of atoms of each element in a compound
What is the molecular formula?
The actual number of atoms of each element in one molecule of a substance
How do you determine the a formula when given percentages?
Work out the number of moles
Divide each by the smallest number of moles
If you have fractions multiply up
Write the formula
What is the molar gas volume?
The volume of 1 mol of gas under specified conditions of temperature and pressure (e.g. 24dm³ at 20ºC and 1atm)
How are moles of gas converted to gas volume?
gas volume = number of moles x Vm (24dm³)
Write out the diagram for converting between gas volume, moles, mass of a gas and moles of another substance in in a balanced symbol eqn.
In book
What is Gay-Lussac’s law?
The volume of gases reacting in the same conditions are equal to the ratio in the balancing equation.
What does sodium hydroxide do in a gas equation?
Uses up all of the CO2 so the volume that is absorbed is the volume of CO2
What is the significance of the resulting mixture being cooled to room temperature?
The water cools to a liquid meaning it is no longer involved in the gas equation. You only need moles of the hydrocarbon, oxygen and water.
What is the formula for % yield?
actual yield
Percentage yield = ————————- x 100
theoretical yield
What is the formula for % Atom economy?
mass (RFM) of desired product
% Atom economy ———————————————– x100
total mass (RFM) of products
What does a high % yield indicate?
The reaction if efficient in converting reactants to products.
