Gen 1 - Stochiometry Flashcards
What is a molecule ?
The smallest unit of a compound that presents the properties of that compound.
What is the empirical formula of a compound ?
The simplest whole number ratio between the numbers of atoms of different elements that make up the compound.
What is the molecular formula of a compound ?
The number of the different atoms that make up a molecule
What is Avogadro’s number ?
The number of atoms in 12g of the most abundant carbon isotope.
Why do we need Avogadro’s Number ?
Large numbers of molecules need to be observed in reactions to bring microscopic chemical reactions to our macroscopic scale.
How do you calculate moles of an element or compound ?
What is the difference between the atomic weight of an element, and the mass of a single atom ?
Atomic weights are dimensionless numbers based on Carbon-12 as the reference standard Isotope. The mass of a single atom can be measured experimentally (!)
What is an Isotope of an element ?
An atom of an element with the same number of protons but a different number of neutrons.
Define atomic weight
The weight in grams of a mole of atoms
Define molecular weight
The weight in grams of a mole of molecules
How would you calculate % yield ?
How would you calculate theoretical yield ?
Theoretical yield is the calculated amound of product that can be predicted from a balanced chemical equation.
Give two examples of double replacement reactions
- Precipiation
- Acid-Base neutralisation
Define Oxidation
- An increase in Oxidation number
OR - Loss of one or more electrons
(Oxidation Is Loss)
Define Reduction
- Decrease in Oxidation number
OR - Gain of one or more electrons
(Reduction Is Gain)
Is Oxidation state equal to Ionic charge ?
No.
Monatomic ions are the only species where charges and oxidation numbers coincide.
What is the oxidation state of an uncombined element ?
In elementary substances, the oxidation number of an uncombined element regardless of whether it is monatomic, diatomic or polyatomic is always ZERO.
What is the oxidation number of an Ion ?
In monatomic ions, the oxidation number of the element that makes up the ions is equal to the charge of the ion.
What is the sum of the Oxidation numbers in a neutral molecule ?
Zero.
What is the sum of the Oxidation numbers of a Polyatomic Ion ?
Equal to the charge of the Ion.
What is the Oxidation number of Hydrogen ?
+1
What is the Oxidation number of Oxygen ?
-2.
What is the Oxidation number of the Alkali Earth Metals ?
E.g. Be, Mg, Ca, Sr
2+
What is the Oxidation number of the Alkali metals ? E.g. H, Li, Na, K
+1
Name 3 common reducing agents
- Lithium Aluminium Hydride LiAlH4
- Sodium Borohydride (NaBH4)
- Ferrous Ion (Fe2+)
Name 5 common Oxidising agents
- Iodine (I2) and other Halogens
- Permanganate salts (MnO4)
- Peroxide compounds (H2O2)
- Ozone (O3), Osmium Tetroxide (OsO4)
- Nitric Acid (HNO3), Nitrous Oxide (N2O)
