chemistry topic 3 Flashcards
what is The relative atomic mass
The relative atomic mass of an element is the mass of an atom compared to the mass of a Carbon 12 atom.
where can we find the relative atomic mass of an atom
the top number of the atom on the periodic table
what is the Relative formula mass (Mr)
Relative formula mass (Mr) of a compound is the sum of the relative atomic masses of the atoms in the numbers shown in the formula.
what makes a balanced equation
both sides of the equation have the same relative formula mass
what is the Law of conservation
no atoms are lost or made during a chemical reaction so the mass of the product equals the mass of the reactants.
why might Some reactions may appear to involve a change in mass
because a reactant or product is usually a gas and its mass has not been taken into account.
what is One mole of a substance
One mole of a substance is just the amount of that substance that contains an Avogadro number of particles
what is the formula for finding the no. of moles
No. of moles = Mass (g) / Ar or Mr (From periodic table)
whats the formula for %mass
% mass = Ar or Mr of Element / Mr of Compound X 100
what is the formula for %yield
Percentage Yield =Actual Yield / Theoretical Yield × 100
what is the Theoretical yield
What you calculate to get from an equation
what is the actual yield
What you actually get after carrying out the reaction and
taking measurements (weigh it)
what are some reasons the actual yield might me less than the Theoretical yield
-Incomplete reactions – some of the reactants don’t react
-Losses during preparation -some of the reactants don’t make it to the reaction
-Unwanted reactions – other reactions occur producing
different products.
what is atom economy
atom economy is the mass of product you want as a % of the
mass of all the products you make
what is the formula for atom economy
atom economy = mass of useful products / mass of all products x 100
