Quantative Chemistry Flashcards
How do you calculate the mass of an element in a compound?
Ar x number of atoms of that element / Mr of the compound
x 100
What is a mole?
An amount of a substance
Formula to work out the number of moles
Mass in g / Mr
What happens to the mass in a chemical reaction?
Mass is always conserved as no atoms are destroyed and no atoms are created
When a mass is conserved, what does this mean?
Means there are the same number and types of atoms on each side of a reaction equation and is because no mass is lost or gained so we say it is conserved
When gas is involved, what seems to happen to the mass?
May see a change in the mass during a reaction as if the mass increases, probably a reactant is a gas and the products are solids. Liquids or aqueous
How do you work out the concentration?
When lots of substances are dissolved in a solution and the amount in a certain volume of a solution is called concentration
What formula is used to work out concentration?
Mass of solute/ volume of solute
What is the formula of concentration when give in MOLES?
Number of moles of solute / volume of solute
How do you work out the atom economy?
Relative formula mass of desired product / relative formula mass of all products x 100
What does the atom economy tell you?
How much of the mass of the reactants is wasted when manufacturing a chemical and how much end up as a desired product
What is the percentage yield?
Amount of a product. Eg. More products you start with, the higher the yield.
*It doesn’t depend on the amount of reactants you start with. It’s the percentage you start with!!
What is the percentage yield formula?
Mass of product actually made / maximum theoretical mass of product x100
