Quantitative Chemistry Flashcards
(21 cards)
What is a molecular formula
Shows the actual number of atoms of each element in a molecule
What is an empirical formula
Formula which shows simplest whole number ratio of atoms of each element in a compound
How is the empirical formula of a compound determined
Finding the mass of each element present in a certain mass of compound and finding simplest ratio between them
What is the formula for moles
Moles = Mass / Mr
What does water of crystallisation mean
Water that is chemically bonded into the crystal structure
Salts can be ______ or _______
Hydrated or Anhydrous
What does it mean when salt is hydrated
Solid crystals contain water of crystallisation
What does it mean when salt is anhydrous
Substance doesn’t contain water of crystallisation
What is the formula for hydrated copper sulfate
CuSO4.5H2O
What happens if hydrated copper sulfate is heated
Dehydrated occurs and water of crystallisation is removed
What happens if water is added to anhydrous coper sulfate
Becomes hydrated and changes from white to blue
what is the process of the removal of water of crystallisation
- Weigh a compound
- Heat the compound
- Re-weigh
- Heat and re-weigh again
- If the masses are the same, take this as the final mass.
If the masses are different, keep heating and re-weighing until
you get two masses the same, this way you know you have
removed all the water
What is the process of removal of water of crystallisation known as
Heating to constant mass
What is the difference in mass from the beginning in heating to constant amss
mass of the water of crystallisation
What is the degree of hydration
Number of moles of water of crystallisation chemically bonded in 1 mole of the compound
What are the three steps for calculating how many water molecules are associated with each salt crystal
Work out moles of the salt and water
Work out the simplest ratio
Write the formula
What is concentration of a solution
Calculated by the number of moles of a substance in one litre
What are the units for concentration of a solution
mol / dm3
What is the conversion for cm3 into dm3
1 dm3 = 1000 cm3
What is atom economy
Measure of how efficient a reaction is, how much of the reactants are converted to the desired products
What is the Atom Economy formula
(Mass of desired products divided by total mass of all products) x 100
