quantitative chemistry Flashcards
what is a mole
the unit used to measure the amount of a substance
Also the a mole is the relative atomic mass of an element in grams, or the
relative formula mass
(Mr) in grams if it’s a
compound
what is the Avogadro constant
6.02*10^23 is 1 mole.
what is relative formula mass
the sum of all the relative atomic mass in a compound.
what is relative atomic mass
average mass of an element derived from an element.
what is the symbol for a mole
mol
what is the symbol of relative formula mass
Mr. the r is lower than the m
what is the symbol of relative atomic mass
Ar. the r is way lower than the m
how can you balance equations
you can use moles
if the Mr is the same on both the reactant and product side then equation is balanced.
counting the number of the atoms.
what does the law of conservation of mass state
in a chemical reaction, no atoms are created or destroyed. the total mass of the products is equal to the total mass of the reactants.
how to calculate the number of moles
mass in g/ relative formula mass
How to calculate relative formula mass in terms of mol
Mr = mass÷mol
How to calculate mass in terms of moles?
Mass = relative formula mass * mol
How to calculate the percentage by mass of a an element in a compound
Total RAM of element/ relative formula mass of compound
What is a limiting reactant
It limits amount of product in a chemical reaction and it’s also the one that’s one fully used up
Why do we add reactants in excess
To make sure reactants are fully used up
What is the relationship between the limiting reactant and the product
Directly proportional. They affect each other
What is concentration in terms of mass
The mass of solute in a given volume of solution
How do you calculate concentration in terms of mass
Mass(g) / volume(dm cubed)
What is concentration in terms of mol
The moles of solute in a given volume of solution
How to calculate concentration in terms of moles
Moles/ volume
How to convert from mol/DM cubed to g/dm cubed
And vice versa
G/dm3 = Mol/DM cubed times Mr
Mol/dm3 = g/dm3 / Mr
How does mass affect concentration
If we increase the mass and keep the volume the same, then the concentration increases
How does volume of solution affect concentration
If we increase the volume of solution, and keep the mass the same, concentration decreases
How to calculate percentage yield
Actual yield/ theoretical yield× 100
Why can’t you always get a 100% percentage yield
Some products gets lost during reaction
Reversible reactions
not all the reactants react
unexpected chemical reactions
how to calculate volume of a gas
mol * 24
how to calculate atom ecocnomy
MR of desired of products / MR of all reactants * 100
what is the atom economy for a reaction with one product
100%
why is it important to consider atom economy
- Raw materials are expensive, so if they are generally going to be converted into waste, it’s less profitable.
- Less sustainable to use large amounts of reactants to make tiny amount of products.
- Waste products are expensive to get rid off
