Chapter 5 : Quantifying chemistry Flashcards Preview

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Flashcards in Chapter 5 : Quantifying chemistry Deck (17):
1

Standard measure

Carbon-12
It is used as the standard for comparing relative atomic masses

2

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

3

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

4

Relative abundance

How much of an isotope is present compared with other isotopes in that element

5

Relative atomic mass

Represents the average mass of one atom taking into consideration the number of isotopes and their relative abundance

6

Relative atomic mass calculation

(RIM of first isotope x abundance) + (RIM of second isotope x abundance) ...
divided by 100

7

Relative molecular mass

The sum of the relative atomic masses of elements in the formula

8

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

9

Avagadros number

6.02 x 10^23

10

Molar mass

Is the mass of 1 mol of the element

11

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

12

Changing mass to moles and moles to mass

n=m divided by M
m= n x M

13

Percentage composition

The composition of a compound is often expressed in terms of the percentage that each element contributes to its mass

14

Formula for percentage composition

% of x in compound = mass of x in 1 mol of compund divided by molar mass of compund
x 100

15

Calculating percentage compostion of hydrated compunds

They can be calculated when both the hydrated compound and the anhydrous compound masses are known

16

Empirical formulas

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

17

Molecular formulas

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