Unit 1.1 - Formulae and equations Flashcards
Sulfur dioxide
SO2
Methane
CH4
Hydrocloric acid
HCL
Sulfuric acid
H2SO4
Nitric acid
HNO3
Ethanoic acid
CH3CO2H
Ammonium (the ion)
NH4+
Ammonium chloride
NH4CL
Which compounds can I figure out myself?
All of the sodiums, coppers and calciums
Which ions have a +1 charge that can’t be figured out using the Periodic Table?
Silver (Ag+) and Ammonium (NH4+)
Which ions have a 2+ charge that can’t be worked out with the Periodic table?
Copper (II) (Cu2+)
Iron (II) (Fe2+)
Zinc (Zn2+)
Lead (Pb2+)
Which ions have a +3 charge that cannot be worked out with the Periodic table?
Iron (III) (Fe3+)
Which ions have a 1- charge that cannot be worked out using the Periodic Table?
Hydrogencarbonate (HCO3-)
Hydroxide (OH-)
Nitrate (NO3-)
Which ions have a 2- charge that cannot be worked out using the Periodic table?
Carbonate (CO3 2-)
Nitrates symbol and solubility rule
NO3-
All are soluble
Chloride, Bromide and Iodide symbols and solubility rule
ALL SOLUBLE
Except…..
Ag+ and PB2+
OH AND COPPER TOO NOW APPARENTLY
Which ions go together in a group of three to share the same solubility rule?
Chlorides, Bromides and Iodides
Carbonates symbol and solubility rule
CO3 2-
ALL INSOLUBLE
Except…..
Na+, K+, NH4+
Symbol for sulphates and solubility rule
SO4 2-
ALL SOLUBLE
Except……
Pb2+, Ba2+, Sr2+
Ca2+ is sparingly soluble
Symbol for hydroxides and solubility rule
OH-
ALL INSOLUBLE
Except…… Na+ and K+
Ba2+ and Ca2+ are slightly soluble
What do you do with a solid compound (s) if writing an ionic equation and why?
Leave it whole as it cannot dissolve in water to form ions
What does (aq) mean in an equation?
That it’s aqueous in water and can thereofore be dissolved in water
Steps to writing ionic equations
1- Word + chemical formula
2 - Write formula of ions formed (remember solids cannot dissolve to form ions)
3 - Omit spectator ions (if they appear on both sides, they do not take part in the reaction and can be cancelled)
Ammonia (the compound)
NH3
What are four things to remember when writing ionic equations?
1 - state symbols (aq or s)
2 - use the correct little ion charges
3 - numbers that were only there for balancing purposes in the compound turn into large ones when split into its separate elements, for example when compounds dissolve in aqueous solution
4 - numbers that are actually part of the compound remain the same, still written as little numbers
(For example for 3 and 4 - Ba(NO3)2 (s) (the two should be small)
Would be Ba 2+ + 2NO3 (the threes should be small lol)
Atom
The smallest part of matter that can exist on its own
Molecule
Two or more atoms combined chemically. Can be the same elements or different ones
Ion
A charged particle
Compound
A substance in which two or more elements are chemically combined - may be covalent or ionic compounds
Which three ions go together with the same solubility rule as eachother? Plus, what is this rule?
Chloride, Bromide and Iodide
All are soluble in water, expect for lead and silver
What do you call the substances that react?
Reagents
What type of equations always require state symbols?
Ionic
What do you call the solid that forms when two solutions react? How would this be written in an ionic equation?
Precipitate
With an (s), without charge as it hasn’t dissolved in the water to form ions
Percipitate
Solid that forms as two solutions react
Which formulas are written without charge in ionic equations?
Elements
Covalent compounds (H20 for example)
Insoluble compounds (CuO for example)
What are the diatomic elements? How can we remember them?
Hydrogen, nitrogen, fluorine, oxygen, iodine, chlorine, bromine
(have no fear of ice cold beer)
What are oxidation states used in?
Molecules or ions
Also covalent structures, where complete transfer of electrons does not occur
What do oxidation states show?
Used to show how many electrons the atom has used in bonding
What’s the first oxidation rule?
(give an example)
The oxidation state of an uncombined element is always zero
O2 = 0
What’s the second rule of oxidation states?
In a compound (contains two elements), 1 element has a positive oxidation state whilst the other has a negative oxidation state
The negative oxidation state is assigned to the more electronegative element
The sun of the oxidation state is zero
In a compound, which element has the negative oxidation state?
The more electronegative element
What is the sum if the oxidation state in compounds?
zero
Give an example of the oxidation states in a compound
NaCl
Na oxidation state = 1
Sum of oxidation states = 0
Therefore, Cl = -1
What’s the third oxidation state rule?
In ions, the sum of oxidation states is equal to the charge of the ion
Give an example of oxidation states in ions
VO2+
Sum of oxidation states = 2
O oxidation states = -2
Therefore, V oxidation state = 4
What’s the fourth oxidation states rule?
Some elements have specific oxidation states
Which group one elements have an oxidation state of 1?
Li, Na, K
Which group 2 elements have an oxidation state of 2?
Mg, Ca, Sr, Ba
What group three elements have an oxidation state of 3?
Al
Hydrogen oxidation state
+1
(except in metal hydrides)
Oxygen oxidation state
-2 (except hydrogen peroxide- H202-1)
Chlorine oxidation state
-1 (except with oxygen (variable) eg. chlorate)
Which elements have exceptions with their oxidation states?
Hydrogen and Chlorine and Oxygen
Which elements have specific oxidation states?
Some group 1, 2 and 3, hydrogen, oxygen and chlorine
Redox reaction
A reaction in which both oxidation and reduction take place
Oxidation
Removal (loss) of electrons = more positive species
= oxidised
Reduction
Gain of electrons = more negative species
=reduced
Oxidising agent
A species that oxidises another and is reduced in the process
Reducing agent
A species that reduces another and is oxidised in the process
What’s the pneumonic to remember the redox reactions?
OIL RIG
How many elements are we expected to say the oxidation state of if there’s multiple?
Just one
What signs do you need to remember to use when writing oxidation states?
Plus or minus
What do we ignore when working out whether oxidation and reduction happened?
The big numbers in front
Disproportionation
When the same element gets oxidised and reduced during the reaction
What do you call when the same element gets oxidised and reduced during a reaction?
Disproportionation
Can you put 1/2 in front of a compound in a formula?
Apparently, an official WJEC past paper said so so we’re going with yes
Oxides symbol and solubility rules
O2-
Insoluble
except
Na, K, Sr, Ba
Ca sparingly soluble
What IS hydrogen peroxides oxidation state?
-1
Which element should you leave until last to make balancing equations easier?
Oxygen
Phosphate ion
Po43-
Lead ion
Pb2+
Phosphoric acid
H3PO4
Which numbers do we ignore when looking at redox reactions to figure out oxidations and reductions?
The big AND small numbers. Just look at the charges
Do we have to balance the oxidation states in a compound when working out whether elements have been oxidised or reduced?
No, just look at their charges on the periodic table
(but still follow uncombined elements rules)
What forms basic oxides?
Group 1, 2 and lanthanides
What is the oxidation state of hydrogen in metal hydrides?
-1
Oxygen oxidation state exception
-2 except in hydrogen peroxide H202, where it’s -1
What’s the oxidation state exception with chlorine?
-1 usually except with oxygen (variable) eg- chlorate
Which other element always has the same oxidation state and what is this?
Florine, that’s always -1
What’s a shortcut for working out oxidation states in complex ions like Cr(H20)6^3+?
The compound’s oxidation state is 0
So (H20) = 0
That leaves Cr6^3+
Which is an uncombined element and an ion with a 3+ charge, so it’s just 3+
Do you use the little numbers when working with oxidation states?
Yes lol
What’s important to remember when writing out nuclear decay equations?
Whatever is decaying gets it’s own side of the equation
Which ions have the same solubility rules as carbonates?
Phosphates and sulphides (s - not to be confused with sulphates!)
What’s an element?
a substance with only 1 type of atom (has its own symbol on the periodic table)
What do I need to stop forgetting for compound formulas?
Brackets! (Especially with hydroxide)
What’s the rule to remember for zeros in significant figures?
Zeros are only significant after a figure
What significant figure do we round to if asked to round to an ‘appropriate’ number of significant figures?
The least amount seen in the question
How do we convert from cm^3 to m^3?
Divide by 100^3
(So, divide by 1,000,000)
With what type of compounds do you take into account the big numbers when calculating the molecular mass?
Hydrides - include water
(E.g - Cuso4.7H20 DOES take into account the 7)
Metal hydride
Metal with covalently bound hydrogen
Zinc ions
Zn2+
Under what conditions is oxygen’s oxidation state no longer -2?
-In peroxides
-In F20
(Both -1 instead)
Where are the halogens on the periodic table?
Group 7
What are the halogens common oxidation states?
-1 (as expected)
Spectator ions
The same on both sides of the reaction - can cross them out of ionic equations as they’re not involved in the reaction
In which order to we write out the letters in compound equations?
CHO
(the rest in alphabetical order)
What is the compound formed from CO3 and H2?
NOT H2CO3 but…
CO2 and H2O
What are two things to remember about the diatomic elements?
-Only write them as diatomic if they’re existing alone
-No need to be diatomic as ions
Do we split water into its ions? Why?
No, we write its state symbol as (l) for liquid, which has the same effect as (s)
