Amount of substance Flashcards
What is a diatomic molecule?
A diatomic molecule is an element that exists as a pair as opposed to on it’s own
What are the seven diatomic molecules you need to know?
Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, Iodine
What does the amount of substance tell us?
The number of particles in a substance
What is amount of substance measured in?
Moles
What is avogardo’s constant and what does it tell us?
Tells us the number of particles in one mole of carbon-12 and the number is equal to 6.02x10^23
Define molecular formula
Number and types of atoms present of each element in a molecule
Define empirical formula
The simplest whole number ratio of atoms of each element in a compound
What is a hydrated salt?
A salt that contains water molecules within its structure
What is the water within the structure known as?
Water of crystallisation
What are the errors when calculating the formula of hydrated salt and why can they occur?
- All water was not lost in the evaporation stage meaning some remain within the
structure - The was further decomposition of the structure meaning something was given off that
wasn’t just water
How do you reduce these margins of error?
- Always heat until it is a constant mass
- Don’t heat it too strongly so that the compound doesn’t overheat and evaporate itself
Define standard solution
A solution of known concentration made in a volumetric flask
What does the molecular gas volume tell us?
That at room temp and pressure (100kPa and 25 degrees C) 1 mole of the substance of a gas occupies 24dm^3
What is the ideal gas equation?
pV = nRT p - pressure (pascals) V - volume (dm3) n - moles R - constant value of 8.31 T - Temperature (K or C+273)
What does atom economy tell us?
How well atoms are used in a reaction and is useful for sustainability to ensure the smallest about of product is wasted
