C4 quantitive chemistry Flashcards
(20 cards)
What is the conservation of mass?
That atoms cannot be created or destroyed
When a metal forms a metal oxide, why does the mass increase?
Because oxygen atoms from the air have been added
When an acid reacts with a metal, why does the mass decrease?
Because a gas is produced and escapes
What is relative formula mass?
The sum of the relative masses of each atom in a compound
The relative atomic mass of an element compares the mass of an element with the mass of an atom of
Carbon-12
What are the four state symbols and what do they stand for?
(s) solid
(l) liquid
(g) gas
(aq) aqueous
What symbol do we use for relative formula mass?
Mr
(HT) What is a mole?
A number of particles (equal to avogadro’s number)
(HT) What is avogadro’s number?
6.022 x 10^23
(HT) What formula relates moles, mass and Mr?
Moles = mass / Mr
(HT) What is a limiting reactant?
A reactant that does not have enough mass to react with all the product
What is the yield of a chemical reaction?
The amount of useful product
What is the theoretical yield of a chemical reaction?
The yield which you would expect to get in a reaction
What is the percentage yield of a chemical reaction?
The amount of actual produce divided by the theoretical yield
What is the % yield almost never 100%?
Reversible reaction, loss of product on separation, unexpected side reactions
What is atom economy?
The amount of starting material that ends up as useful product
Why is atom economy important?
Economic and sustainability reasons
How is atom economy calculated?
(Mr desired product / Mr all reactants) x 100
(HT) What do the moles of gases and their volumes have in common?
At the same temperature they occupy the same volume
(HT) What is the volume of one mole of any gas at room temperature and pressure?
24 dm3
