topic 3 quantitaive chemistry Flashcards
define relative atomic mass and relative formula mass
Ram – average mass of atoms in an element taking into account masses and abundance of its isotopes
– Some of rams of all atoms in the formula
what is Avogadro constant?
The number of atoms, molecules or ions in a mole of a given substance. The value of the constant is 6.02×10 to 23
what is the formula that links mass, molecular mass and moles together together?
mass=Mr x moles
State what we mean by a limiting reactant in a chemical reaction
in the chemical reaction involved in two reactants, it is common to use an excess of one of the reactants to ensure that all of the other reactants is used. The reactant that is completely used up is called the limiting reactant because it limits the amount of products.
Write down the two formula that link concentration, moles/mass and volume together
concentration (g per dm3) =mass(g)/volume (dm3)
concentration (mol per dm3)=nr of moles/volume (dm3)
what is the molecular volume of a gas at room temperature and pressure?
One mole of a gas at room temperature temperature and pressure occupied 24 dm squared
what is titration?
A technique for finding the concentration of a solution by reacting unknown volume of this solution with a solution of a known concentration
Why is it not always possible to obtain the theoretical amount of product in a chemical reaction?
The reaction may not go to completion because it is reversible. Some of the product may be lost when it is separated from the reaction mixture. Some of the reactants may reactant way different to expected reaction.
how is percentage yield of a product in a chemical reaction?
% yield=acutual mass of product
———————————- x 100
Maximum theoretical mass of product
what is atom economy?
A measure of the amount of materials that end up as useful products. It is a ratio of the relatively formula mass of a desired product to the sum of a relatively formula mass of reactants.
