Module 2:Foundations In Chemistry Flashcards
Carbon-12
The standard isotope which is used to base all atomic masses .The international standard for the measurement of atomic masses
Relative isotopic mass
Relative isotopic mass is the mass of an isotope relative to 1/12 th of an atom of carbon-12
Relative atomic mass
Is the weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12
Mass to charge ratio formula
Mass to charge ratio M/Z = relative mass of ion / relative charge on ion
Binary compound
Contains two elements only
Polyatomic ions
An ion may contain more than one element bonded together.
Avogadro constant
6.02 x 10^23
Mole / Amount
Amount n = mass m/molar mass M
Molecular formula
The number of atoms of each element in a molecule e.g. H2,F2
Empirical formulae
The empirical formula is the simplest whole number ration of atoms of each event in a compound e.g. C2H6 would become CH3
Relative molecular mass
Compares the mass of a molecule with the mass of an atom of carbon-12
Relative formula mass
Relative formula mass compares the mass of a formula unit with the mass of an atom of carbon-12
Standard solution
A solution of a known concentration
Molar gas volume
The volume per mole of gas molecules at a stated temperature and pressure
Mole formula
Mole=conc x volume
What are the assumptions for the molecules making up an ideal gas
-random motion
-elastic collisions
-negligible size
-no intermolecular forces
Ideal gas equation and values
pV=nRT
T:temperature (+273K)
R:ideal gas constant (8.31Jmol^-1K^-1)
n:amount of gas molecules (mol)
V:volume(m^3)
p:pressure(Pa)
Conversions for ideal gas equation
Cm^3 to M^3 = x10^-6
dm^3 to m^3 = x 10^-3
Degrees Celsius to K(kelvins)=+273
kPa to Pa = x10^3
Stoichiometry
In a balanced equation , the balancing numbers give the ratio of the amount in moles of each substance.This ratio is called stoichiometry of the reaction
Percentage yield equation
Percentage yield = )
(actual yield / theoretical yield) x 100
Limiting reagent
The reactant that is not in excess will be completely used up first and stop the reaction
Atom economy
Atom economy=(sum of molar masses of desired products/ sum of molar masses of all products) x 100
Strong acid
A strong acid like HCl releases all its hydrogen atoms into a solution as H+ ions and completely dissociated in aqueous solution
Weak acid
A weak acid such as ethanoic acid , CH3COOH , only releases a small proportion of its available hydrogen atoms into solutions as H+ ions .A weak acid partially dissociates in aqueous solution
Bases
A base neutralises an acid to form a salt
Alkali
An alkali is a base that dissolves in water releasing hydroxide ions (OH-) into the solution
Name the Salts of the following acids : hydrochloride acid , sulfuric acid , ethanoic acid, nitric acid
HCl: chloride
H2SO4:sulfate
HNO^3:nitrate
CH3COOH:ethanoate
What is titration
A technique used to accurately measure the volume of one solution that reacts exactly with another solution.It can be used to:
-Finding the concentration of a solution
-identification of unknown chemicals
-finding the purity of a substance
Oxidation number
It is based on a set of rules that apply to atoms and can be thought of as the number of electrons involved in bonding to a different element .
Rules for elements oxidation number
The oxidation number is always zero for elements
-in a pure element any bonding to atoms of the same element
-So in H2, O2, P4 and Fe the oxidation number of each of the elements is 0
Rules for compounds and ions oxidation number
-Each atom in a compound has an oxidation number
-An oxidation number has a sign , which is placed before the number
Oxidation number for O
-2
Oxidation number for H
+1
Oxidation number for F
-1
Oxidation numbers in special cases
H in metal hydrides : -1
O in peroxides: -1
O bonded to F : +2
Oxidation and reduction definition in terms of reactions involving oxygen
Oxidation: addition of oxygen
Reduction: removal of oxygen
Redox in terms of electrons
Reduction: gain of electrons
Oxidation:loss of electrons
OILRIG
What are electron shells
Shells are regarded as energy levels
The energy increases as the shell number increases
The shell number or energy level is called the principle quantum number
What is an orbital
An atomic orbital is a region around the nucleus that can hold up to two electrons with opposite spin
