3.1.2 Amount Of Substance Flashcards
Write the formulas for the following common ions:
Silver
Zinc
Ammonium
Hydrogen
Nitrate
Sulphate
Carbonate
Hydrogencarbonate
Hydroxide
Hydride
Phosphate
Silver - Ag+
Zinc - Zn2+
Ammonium - (NH4)+
Hydrogen - H+
Nitrate - (NO3)-
Sulphate - (SO4)2-
Carbonate - (CO3)2-
Hydrogencarbonate - (HCO3)-
Hydroxide - OH-
Hydride - H-
Phosphate - (PO4)3-
How do we write chemical formulae?
Ensure that the charges on both ions are balanced, and therefore equal and opposite.
Eg. Barium Hydroxide
Ba2+ = 2+ charge and OH- = 1- charge
Ba(OH)2
What is the meaning of the ending ‘ate’?
Contains oxygen
Eg. Sulphate, carbonate, phosphate etc..
General equation for a substance reacting with oxygen?
Substance + oxygen -> oxides
General equation for reaction between metal and water?
Metal + water -> metal hydroxide + hydrogen
General equation for reaction between metal and acid?
Metal + acid -> salt + hydrogen
General equation for reaction between a hydrogencarbonate and acid?
Hydrogencarbonate + acid -> salt + water + carbon dioxide
General equation for the reaction between ammonia and acid?
Ammonia + acid -> ammonium salt
General equation for the thermal decomposition of a metal carbonate?
Metal carbonate -> metal oxide + carbon dioxide
General equation for reaction between metal oxide and acid?
Acid + metal oxide -> salt + water
General equation for reaction between metal hydroxide and acid?
Acid + metal hydroxide -> salt + water
General equation for the reaction between metal carbonate and acid?
Acid + metal carbonate -> salt + water + carbon dioxide
What is a salt?
When the hydrogen ion in an acid is replaced by a metal, it is a salt
-the first part of the salt is from the metal, and the second part is from the acid
-have the names: chloride, sulphate, nitrate and phosphate
How do you know when an equation is balanced?
The equation is balanced when there are the same number of each atom in the reactants, and in the products.
Define relative atomic mass?
The relative atomic mass is the average mass of one atom of an element, compared to one twelfth of the mass of an atom of carbon-12.
Ar = average mass of one atom of an element / 1/12th of the mass of an atom of carbon-12
How is the relative atomic mass of an element calculated?
-from the average mass of the isotopes of an element, weighted to their abundance
Ar = (% abundance 1 x mass 1) + (% abundance 2 x mass 2) etc… / 100
-these values are shown on the periodic table
Define relative molecular mass?
The relative molecular mass is the average mass of one molecule, compared to one twelfth of the mass of an atom of carbon-12.
Mr = average mass of one molecule / 1/12th mass of an atom of carbon-12
What is a molecule?
When there is a set number of atoms, in a set ratio.
What is the relative formula mass?
It is the relative mass used for ionic compounds, and is calculated in the same way as the Mr.
How is the Mr of a molecule found using Ar values?
By adding up the relative atomic masses of all of the atoms present in one molecule.
Eg. CO2 = 12 + (16x2) = 44
What is Avogadro’s constant?
The Avogadro’s constant is the number of particles in one mole of any substance
What is the value of Avogadro’s constant?
6.022 x 10^23
What is a mole?
A mole is an amount of a substance that contains 6.022 x 10^23 particles.
-the Ar or Mr of any atom or molecule will contain 6.022 x 10^23 individual atoms or molecules
-therefore, the Ar of an element is equal to the mass of one mole of its atoms in grams
Eg. Carbon
Ar = 12
Mass of 1 mole of carbon atoms = 12
What is the equation linking mass, mr and moles?
Moles = mass/Mr
Or
Mass = Mr x moles
(Mass is measured in grams)