P1-Topic 3- Quantitative Chemistry Flashcards
What is the law of conservation of mass? 2
no atoms are lost or made during a chemical reaction
the mass of the products
equals the mass of the reactants
What is the relative formula mass of CaF₂
Ar values: Ca = 40, F = 19
40 + 19 + 19 = 78
Do you use big numbers when calculating relative formula mass
no
how you could increase the precision of the results
Measure to more decimal places (higher resoloution)
use a more sensitive balance /apparatus
what is the equation for the percentage by mass of an element ?
total RAM of atoms of that element
——————————— *100
RFM of the compound
What is Avogadro’s constant? 2
The number of atoms, molecules or ions in a mole of a given substance.
The value of the constant is 6.02 x 10²³
State what we mean by a limiting reactant in a chemical reaction 4
In a chemical reaction involving two reactants an excess of one of the reactants is used to ensure that all of the other reactant is used.
completely used up= limiting reactant because it limits the amount of products.
the other is in excess
Write down the two formulae that link concentration, mole/mass and volume together.
Concentration (g per dm³) =
Mass(g)/Volume (dm³)
Concentration (mol per dm³)=
nr of moles/volume (dm³)
what is a limiting reactant
the reactant that is used up / not in excess (since it limits the
amount of products)
which are reactants and which are products
the reactant that is used up / not in excess (since it limits the
amount of products)
what is meant by concentration
the mass of a solute in a given volume of soloution
what gives a higher concentration
a smaller volume or larger mass of solute
what gives a lower concentration
a larger volume or smaller mass of solute
