Chem CT 3 Flashcards
(19 cards)
How to calculate concentration?
mass / volume
what unit is concentration in?
dm cubed
cm cubed to dm cubed
/ 1000
how to calculate the relative formula mass or molar mass or Mr?
add up all the atomic masses in a compound
what does Av mean
Avagadro’s constant = 6.02 x10 23
how to calculate the percentage yield
actual yield / theoretical yield X 100
how to calculate the atom economy
relative formula mass of USEFUL product / relative formula mass of ALL products X 100
how to calculate mol: md dm-3
concentration x volume / 100
what is the law of conservation of mass?
mass at start of reaction = mass at the end of the reaction
how to calculate the volume of a gas
volume/molar volume
explain what the empirical formula
the simplest number ratio of atoms of an element in a compound
what do you do if the ratio in an empirical formula is 1:1.5
times by 2
What is meant by theoretical yield?
the maximum amount of product when reactants have fully reacted.
Why is the actual yield usually less than the theoretical yield in a reaction?
- reaction my be incomplete
- product/reactant lost
- other reactions may occur
how to calculate the volume of gases?
mols times molar volume
How to calculate the limiting reactant?
calculate the Mr
divide the mass by the Mr
put the two answers in a ratio
see which number is bigger
what is the Mr?
the total mass of the atoms using the atomic mass from the periodic table
How to balance equations using moles?
-work out the moles ( mass/Mr)
-work out the ratio (divide by smallest numbers)
-put the ratios in front of the reactants and products
