Chapter 5 : Quantifying chemistry Flashcards
Standard measure
Carbon-12
It is used as the standard for comparing relative atomic masses
Mass spectrometer
Deflects the path of the lightest element the most and the highest charged particle the furthest therefore giving;
No. of isotopes
Relative isotopic mass of each isotope
Percentage abundance of isotopes
Relative isotopic mass
Is the mass of a single isotope and is determined y comparing the mass of ions of the isotope to the value of a standard carbon-12
Relative abundance
How much of an isotope is present compared with other isotopes in that element
Relative atomic mass
Represents the average mass of one atom taking into consideration the number of isotopes and their relative abundance
Relative atomic mass calculation
(RIM of first isotope x abundance) + (RIM of second isotope x abundance) …
divided by 100
Relative molecular mass
The sum of the relative atomic masses of elements in the formula
The Mole
The amount of a substance that contains as many particles (atoms, ion of molecules) as there are atoms in exaclty 12g of the carbon-12 isotope
Avagadros number
6.02 x 10^23
Molar mass
Is the mass of 1 mol of the element
Changing moles to number of particles
n = m divided by M, n = moles, m = mass and M =molar mass
To go from particles to moles you divide by avogadros number, to go from moles to particles you multiply by avogadros number
Changing mass to moles and moles to mass
n=m divided by M
m= n x M
Percentage composition
The composition of a compound is often expressed in terms of the percentage that each element contributes to its mass
Formula for percentage composition
% of x in compound = mass of x in 1 mol of compund divided by molar mass of compund
x 100
Calculating percentage compostion of hydrated compunds
They can be calculated when both the hydrated compound and the anhydrous compound masses are known
