Unit Five Flashcards
Products
The ending materials, located on the right of the arrow
(s)
Solid
(l)
Liquid
(g)
Gas
(aq)
Aqueous
Aqueous
The substance has been dissolved in water
Coefficients
Numbers in front of a compound that tell you how many moles of the compound you have
Diatomic elements
I2 Br2 Cl2 F2 O2 N2 H2
Goal of balancing chemical equations
Make the equation satisfy the law of conservation of matter, with equal amounts of atoms in the reactant and product side
What to do when balancing combustion reactions
Balance carbon first, then hydrogen, then oxygen
Mole
A unit of measure used in chemistry that equals 6.02 x 10^23
What to do if equation has a polyatomic ion on both sides of the equation
Treat it like its own thing
Synthesis: definition, basic form
The combining of two or more substances
A + B —> AB
Decomposition
When one substance breaks down into two or more simpler substances (the opposite of synthesis)
AB —> A + B
Single replacement (single displacement)
When a single element replaces an element in a compound, creating one new compound, and displaces the other element
A + BC —> AC + B
Double replacement
Two elements from two different compounds switch places to form two new compounds
AB + CD —> AD + BC
Combustion
A reaction of a hydrocarbon with oxygen to form water and carbon dioxide (NEEDS OXYGEN AS A REACTANT AND WATER AND CARBON DIOXIDE AS PRODUCTS)
CxHy +O2 —> H2O + CO2
Reactants
The starting materials, located on the left of the arrow
Predicting reaction products
Based on the type reaction, products can be predicted. When reforming products, must break groups into cation and anion, then determine if the the chemical equation needs to be balanced. Also, chemical formulas of ionic compounds must have an overall neutral charge.
Oxidation-reduction reaction (redox)
A type of chemical reaction that involves a transfer of electrons between two species. Synthesis, decomposition, single replacement, and combustion reactions fall under this category.
Precipitation reaction
When an insoluble product forms when two soluble substances react (typically ionic compounds). When a substance is soluble we use (aq), when it’s insoluble we use (s). Use the solubility rules. It’s a type of double replacement reaction.
Neutralization reaction (acid-base)
When an acid reacts with a base to form water and a salt. Acids contain H+ ions AND bases usually contain OH-. When the H+ from the acid combines with the OH- of the base it forms water. The remaining ions combine to form the salt (salt is another term for an ionic compound). MUST HAVE H+ AND OH-. A type of double replacement reaction.
Reduction
Gain electrons
Oxidation
Lose electrons
OIL RIG
Oxidation is loss reduction is gain
First rule for oxidation numbers
The oxidation number of an individual atom is zero
Ex. Mg = 0
Oxidation rule 2
The total oxidation numbers of all atoms in a neutral species is zero and in an ion is equal to the ion charge
Oxidation rule 3
Group 1 metals have an oxidation of umber of +1 and group 2 and oxidation number of +2 (in compounds).
Oxidation rule 4
The oxidation number of fluorine is -1 in compounds.
Oxidation rule 5
Hydrogen generally has an oxidation number of +1 in compounds, unless bonded to a metal where its oxidation number is -1.
Oxidation rule 6
Oxygen generally has an oxidation number of -2 in compounds, with the exception if peroxides like H2O2 where it is -1.
Oxidation rule 7
In binary metal compounds (and ONLY in binary metal compounds):
Group 17 elements have an oxidation number of -1
Group 16 elements have an oxidation number of -2
Group 15 elements have an oxidation number of -3
Solubility rules
Don’t have to memorize the rules but use them from top to bottom (so too gets priority over bottom). If an ion is soluble, then it is (aq). If it is insoluble, then it is (s). If they’re all soluble, then no precipitation reaction occurs.
Net ionic equations
The molecular equation for the reaction. It is without the spectator ions. You don’t need to include anything but the precipitate and the ions that form it.
Complete ionic equation
Shows the dissolved ionic compounds as free ions in solution. Only write the charges for the broken up ionic compounds that are aqueous. Solid precipitated that form remain as a single compound.
Complete ionic equation
Can be simplified by eliminating ions that do not participate in the reaction.
Spectator ions
Ions that are not directly involved in a reaction.
Mole
Unit of measurement used because individual atoms are too small to work with
1 mole/Avogadro’s number
6.02x10^23
Molar mass
The mass of one mole of a substance (specific to whatever you’re talking about)
How to calculate molar mass
List each element in your substance
Record the atomic mass for each element (found on the periodic table) and round to three significant figures
Multiply each mass by the number of atoms contained in the substance
Add up the totals for each element
Unit for molar mass
Grams per mole
G/mol
Particles to moles, moles to grams
Multiply
Grams to moles, moles to particles
Divide
Percent composition
Mass percentage of each element in a compound
How to find percent composition
Get the molar masses of the elements, get the total molar mass of the thing, divide, get percentage
Empirical formula
A formula that shows the ratio of elements in simplest (lowest) terms
Steps for calculating empirical formulas
Convert mass percentage of each element to grams (pretend like there are 100g, so if 70.7% then write 70.7g)
Convert grams to moles using molar mass (divide amount of grams by molar mass)
Compare amounts of moles to find the simplest whole number ratios (divide by the lowest number)
Hydrate
An ionic compound sigh water molecules trapped inside the crystal lattice structure
How to name formulas with hydrates
Normal formula, then add the prefix and hydrate
Ex. Sodium carbonate decahydrate
How to find the percentage of a hydrate
Add the molar mass of the water (18.0 x the prefix) plus the molar mass of the other thing. Divide by the total whichever you’re trying to find.
