Chemical equations, define, write, balance and identify the type of reaction.
Review of compounds and why compounds form.
Why do chemical reactions occur? ___________________________________________________________
Chemical reactions are when a totally ____________________ substance is formed.
Reactants ------à Products
The indicators of a chemical reaction are: _________________________________________________________
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A Precipitate is an _____________ substance that is produced as result of a ______________________
The Law of Conservation of Matter states that (in a chemical reaction) no matter is _____________ or __________________
Whatever _______ we started with on the ______________ side we’re going to have to have on the ________________side.
We do this by making sure _____________ are ___________________. Mean we have the ________ ___________ and types of _______________ on ______________ sides of the -----à.
(g) means the substance is a ________________ (l) means the substance is a ________________
•(s) means the substance is a __________________ (aq) means the substance is _____________________
Aqueous means _________________________________________.
There are 5 main types of reactions
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Combination is also called ________________ and has the general form of _______________________________
Decomposition has the general form of _______________________________
Single Replacement (displacement) has the general form of _______________________________
Double Replacement (displacement) has the general form of _______________________________
Combustion has the general form of _______________________________
Combination or synthesis is when _____things come together to make _____ thing.
__________ and _________ react to form the compound _____________.
The equation is: _________________________________
This is called a ___________ equation since it’s not balanced. There is 1 C on the left, and 1C on the right, but there are 2H on the left and 4H on the right.
Counting Molecules and Atoms: 2H2O
•2 ______________ of water. To count atoms we’re going to use mutiplication. 2x2H= 4H, 2x1O= 2O
In 4 Mg(NO3)2 means 4 of the formula unit Mg(NO3)2
•4 x 1Mg= 1Mg, 4x2N = 8N, 4x6O= 24O
•The 2 and the 4 are called _______________________, just like 5X in math where the 5 is the coefficient.
A balanced chemical reaction: C + 2H2 à CH4
In the Synthesis or Combination Reaction of Mg and oxygen react at high temperature what is formed?
Mg + O2 -à MgO O2 is diatomic when written into reactions
• (How’d I know MgO, well 4 steps: symbols, charges, crossover, reduce)
•To balance it… ___ Mg + ___ O2 -à ___MgO
•1- for all ionic compounds correctly establish their formula
•2-List all elements in the rxn under the arrow
•3-Count the number of atoms of each type on both sides of the equation
•4-Starting with metals change the coefficients until both sides are balanced.
DO NOT CHANGE CHEMICAL FORMULAS themselves. Do NOT change subscripts..ever. You may only change the coefficients.
Balanced equation Examples:
N2 + ______H2à ______NH3
_____Al + ___________F2à _____AlF3
P4 + _____O2 à P4O10
SO3 + H2O à H2SO4
Decomposition: When things decompose they _________ __________. This reaction is where _____ compound breaks down into ________ elements. Iron(III) chloride ___________ at high temperature into it’s elements.
FeCl3 à Fe + Cl2 This is not balanced, also remember that Cl has to be written as Cl2 because it is a diatomic molecule.
Balance:
Electrolysis is when you put a __________ through water. Water turns into it’s ___________. Write and balance the reaction. ___H2O à ___H2 + ___O2
More Examples of Decomposition:
CaCO3 à CaO + CO2 2 HgO à 2 Hg + O2 2 ClO3 à 2KCl + 3O2
Displacements: •These are the 2 hardest to tell apart when starting.
•Single displacements typically have 1 lone element on both sides of the reaction
•Double displacements look like the biggest reactions out there, and you’ll see that the two metals switch places
Single Displacement: •Magnesium metal starts making hydrogen gas when it’s dropped in aqueous hydrochloric acid. What’s the full reaction? ___Mg + ___HCl -à ___ H2 + __
More Examples: 3AgCl + Al àAlCl3 +3 Ag 2Na + H2O -à H2 + 2NaOH Zn3N2 + 3Mg à Mg3N2 + 3Zn
Double Displacement: occur when a more reactive metal displaces a less reactive metal from one of its compounds. Also occur when a more reactive non-metal displaces a less reactive non-metal from one of its compounds.
Spectacular very exothermic 'thermit reaction' which shows aluminium is more reactive than iron. When a mixture of aluminium and iron(III) oxide is ignited with a magnesium fuse (high activation energy), the mixture burns furiously with a shower of sparks to leave a red hot blob of iron and a white as of aluminium oxide
•iron(III) oxide + aluminium ==> aluminium oxide + iron
•Fe2O3(s) + 2Al(s) ==> Al2O3(s) + 2Fe(s)
more reactive copper 'gently' displaces silver from silver nitrate solution to make silvery plated copper
•copper + silver nitrate ==> copper(II) nitrate + silver Cu(s) + 2AgNO3(aq) ==> 2Ag + Cu(NO3)2(aq)
•Double decomposition is chemical reaction that takes place between two compounds, in which the first part of one compound combines with the second part of another compound. The bits left over combine to form the second compound. One of the compounds is usually insoluble.
For example:
if you mix solutions of sodium chromate with lead nitrate you get a yellow precipitate of lead chromate and sodium nitrate is left in solution.
•sodium chromate + lead nitrate ==> lead chromate + sodium nitrate
•Na2CrO4(aq) + Pb(NO3)2(aq) ==> PbCrO4(s) + 2NaNO3(aq)
•This is the yellow pigment Van Gogh used in his paintings and you see it as the road markings you don't park on!
Nonmetal Nonmetal Displacements
•halogen displacement: more reactive chlorine displaces bromine from potassium bromide
•chlorine + potassium bromide ==> potassium chloride + bromine
•Cl2(aq) + 2KBr(aq) ==> 2KCl(aq) + Br2(aq)
or more reactive bromine displaces iodine from sodium iodide
• bromine + sodium iodide ==> sodium bromide + iodine
• Br2(aq) + 2NaI(aq) ==> 2NaCl(aq) + I2(aq)
Combustion Reactions Combustion means burning and fire. What two things does fire require? O2 and something to burn. We normally burn hydrocarbons (Hydro=H, Carbon = C therefore stuff made up of H and C).
•The products are always CO2 and H2O.
•Methane and Oxygen burn write the equation. ___CH4+ ___O2 à ___ CO2 + ___H2O
Acid Base: ( A type of double displacement reactions, except one of the compounds is going to be an acid and the other will be an ionorganic salt) Salt just means combination of a cation and anion in a solid form.
•Hydrochloric acid and sodium hydroxide react together. Write the reaction.
Solubility: •Often times we perform a double displacement reaction to actually collect one of the products. We can make certain compounds crash out of (precipitate) an aqueous solution because of how soluble some compounds are.
•We’ll take two soluble compounds, they will react, and they will typically make one soluble product and one insoluble product.
Dissolving: •So, what happens when an inorganic compounds dissolves (this is totally different than a molecular compound dissolving)?
•Water molecules act as crowbars that split molecules into pieces. The two pieces formed are the cations and the anions.
•When you see table salt it’s the compound NaCl. When you dissolve it in water it’s actually Na+ and Cl-.
Try some more
Molecular Compounds
Spectator •Spectator ions- reactions have components that aren’t that important to the overall effect. We can tell they aren’t that important because they appear on both sides of the chemical equation. They aren’t really participating, they are just hanging out. We call them spectator ions.
Net Ionic Equations
•Net just means overall, so we’re trying to figure out what’s the overall reaction.
•Aluminum chloride and sodium phosphate undergo a double displacement reaction. What precipitates and what’s the net ionic equation?
•AlCl3 + Na3PO4 à AlPO4 + NaCl = skeleton
•AlCl3 + Na3PO4 à AlPO4 + 3NaCl = balanced
•AlCl3(aq) + Na3PO4(aq) à AlPO4(s) + 3NaCl(aq) total eq
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Total Ionic
Net