Molecules Flashcards
What is the empirical formula?
The simplest whole number ratio of atoms of each element present in a compound
What is the molecular formula?
The number and type of atoms of each molecule present - true number of each atom in the molecule
What is water of crystallisation?
Water that is part of the crystalline structure
What way are the water molecules chemically bonded into the crystal structure?
Stoichiometrically
What is an anhydrous substance?
Doesn’t contain any water of crystallisation
What is a hydrous substance?
Contains water of crystallisation
What are the two units for concentration?
- g/dm3
- mol/dm3
What is a standard solution?
A solution of known concentration
How can a standard solution be prepared?
Dissolving a known mass of solid in solvent and making it up to an exact volume
What is the limiting reagent in a reaction?
The reactant that is not in excess, will be used up first and will cause the reaction to stop.
What are standard conditions?
101kPa
298K
What is the ideal gas constant value?
R = 8.314
What is the ideal gas equation? ( only used under standard conditions)
pV = nRT
What is the equation for % yield?
(Actual yield / theoretical yield ) x 100
For what 5 reasons do experiments usually have a % yield less than 100%
1) reaction incomplete
2) gaseous products not collected
3) loss of products on equipment
4) unwanted side reactions
5) reversible reaction
What is the equation for atom economy?
(Mr of desired product / Mr of reactants) x 100
Why is it more economically viable and sustainable for industrial chemical processes to have a high atom economy?
- little or no waste product
- preserves raw materials
