Chapter 5 : Quantifying chemistry Flashcards Preview

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Flashcards in Chapter 5 : Quantifying chemistry Deck (17):

Standard measure

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


Empirical formulas

Is the simplest whole number ratio of atom or ion present in a compound


Molecular formulas

Represents the actual composition of a compound that is made up of molecules