C9- Calculations Involving Masses Flashcards
What’s the empirical formula
The simplest whom number ratio of atoms or jons of each element in a substance
What’s the molecular formula
It represents the actual number of atoms of each element in one molecule
The formula of a compound is…
It’s molecular formula of its a simple molecule or the empirical formula if it has a giant lattice structure
What’s the relative formula mass
M(little bottom right corner r) of a substance is the sum of the relative atomic masses (Awith little r in bottom right) of all atoms or ions in its formula
How is empirical formula calculated
MRDDSF
Mass(g)
Relative atomic mass
Divide the mass of each element by its relative atomic mass
Divide the answer by the smallest number to find its simplest ratio
Simplest Form is left (empirical formula)9
What’s the law of conservation of mass
The solution is equal to the mass of the solvent and the mass of the solute
The overall mass of the substances does not change
How can you calculate the concentration of a solution in gdm^-3
Concentration = mass of solute in g divided by volume of solution in dm^3
1000cm^3 = 1dm^3
Lead nitrate solution reacts with potassium iodide solution to form what
A yellow precipitate of lead iodide and a colourless solution of potassium
This is as an example of a closed system
What’s a closed
System
Where no new substances are added or removed
What’s a non enclosed system
When in a reaction the mass changes eg Becuase the gas produced can escape
Or some products react with oxygen in air
Tell me how to calculate the masses of reactants or products
Write the Balanced equation
Calculate relative formula masses of the substances need
Calculate ratio of masses. - multiply M(bottom right little r) values by the balancing numbers shown in the equation)
Work out the mass for 1g of reactant product
Scale up or down from 1g to mass you are given
What is a mole
6.02 X 10^23 (Avogadros constant) there are this many particles in 1 mol of a substance - can be atoms molecules or ions
What’s the mass of 1 mol if a substance
Is the relative atomic mass of formula mass of a substance in grams
Tell me the mass, relative atomic mass and miles formula triangle
Mass in g on top and relative atomic/formula mass X moles on the bottom
What’s the limiting factor
The amount of product formed is determined by the amount of reactant that is not in excess (and so is used completely)
