Quantitative Chemistry Flashcards
(15 cards)
What is conservation of mass
No atoms are lost or made during a chemical reaction
Symbol equations must balance
The mass of the products equals the mass of the reactants
When does a reaction to appear to increase / decrease in mass?
When one of the reactants / products is a gas
How to calculate relative formula mass (Mr) of a compound of complex molecule? What unit is used?
Add together relative atomic masses of every atoms in the substance
Measured in g/mol
What is a mole?
6.02x10^23 (Avagadro’s constant)
How many atoms does 1 / 0.5 / 2 moles of a substance contain?
1 = 6.02x10^23
0.5 = 30.1x10^23
2 = 1.204x10^24
What is relative atomic mass?
How much 1 mole of atoms weighs (in grams)
How to calculate mass using moles?
mass = Mr x mole
What is theoretical yield?
The theoretical maximum amount of product able to be made using a reactant
What is concentration?
How do you calculate this?
How do you calculate this using moles?
A measure of how many dissolved particles are in a set volume of a solution.
mass of solute (g)/ volume of solvent (dm^3)
moles of solute (g)/ volume of solvent (dm^3)
What is a limiting reactant?
A reactant that runs out first, limiting the amount of product made
What is an excess reactant
A reactant of which there is excess when the reaction is complete
How to work out percentage yield
(mass of product made / theoretical mass of product made) x 100
Why is percentage yield never 100%?
Reaction may be reversible
Reaction may not go to completion
Reactants may react in different ways
Product may be lost during extraction
What is atom economy
What proportion of reactants are turned into useful products
How to work out atom economy
(mass of useful product / total mass of product) x 100
