exam 1 review Flashcards
addition and subtraction sig fig rules
least amount of decimals
multiplication and division sig fig rules
least amount of sig figs
how to figure out # of protons, neutrons , electrons, charge
protons is on the periodic table and is the same as electrons. neutrons is the isotope number minus protons number. charge is how many protons vs electrons
what do the letters a and z represent when it comes to the periodic table and protons neutrons and electrons
A= the number of protons and neutrons Z= the number of protons
how to determine empirical formula
change percents to grams, divide by their molar mass, then divide them all by the smallest answer
how do you complete chemical reactions
outter-> outter, inner-> inner, then balance
how to write total ionic and net ionic equations
make sure it is balanced
total: separate each compound, write them (and if their are multiple from balancing as a constant in front), their charge, and their state of matter. add them all and keep solids together
net: cancel out all compounds that appear on either side and rewrite
be able to balance reactions
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how to find theoretical yield
use given grams of reactant, divide by 1/molar mass, multiple by mole to mole ratio (balanced eq, product over reactant), multiply by 1/ molar mass of product, use sig figs
how to find percent yield
actual yield divided by theoretical yield x 100
how to find atomic mass
multiply atomic mass by isotopic abundance and add them all up
how to find isotopic abundance
first#x times second#(1-x) = atomic mass of element
solve for x and multiply by 100, (that = first % abundance) subtract that number by 100 to get the second abundance
how to calculate moles given grams
take the given grams and divide by molar mass (number of periodic table)
how to calculate atoms given grams
take given grams, divide by molar mass, multiple by avogadros number
how to calculate grams given mols
multiply given moles by molar mass
how to calculate mass percent
find molar mass of element you want (make sure to multiply it by the correct amount of atoms in the formula), divide by total molar mass of the compound, multiply by 100
how to find mass of a compound given the mass of one element in the compound
multiply given mass by 1 mol compound/how many mols of the element are in the compound, by molar mass/1 mol = grams of compound
How to find formula units
multiply grams by avagadros number
how to find molecular formula given percents of each element
find empirical formula (percent x 1mol/molar mass, divided by smallest #): divide the given molar mass of the compound by the molar mass of the empirical formula. multiply all of the subscripts by that number
how to write combustion reactions
compound + O2 -> CO2 + H2O
how to do stoichiometry
given grams of compound x 1 mol/ molar mass compound x molar ratio (molCO2/mol compound) x molar mass of CO2/ 1 mol = grams CO2
what are the oxidation number rules
elements by themselves = 0
group1A= +`1
group2A= +2
Halogens; usually -1 (positive with oxygen)
monotomic ions= ion charge (ex: N3- = -3)
H= +1 with nonmetals, -1 with metals
O= -2, -1 in peroxide H2O2
F= always -1
Neutral compounds sum= 0
polyatomic compounds(anything w/ charge) sum= ion charge
multiply oxidation numbers by the number of atoms then solve for 0 or ion charge
oxidation and reduction definition and rules
oxidation: loss of electrons O.N. goes up
reduction: gain of electrons O.N. goes down
oxidized= reducing agent
reduced= oxidizing agent
scientific notation rules
big-small = positive small-big= negative
Celsius to K
k= c+ 273.15
f to celsius
c= (f-32) x (5/9)
density formula
d= m/v
molarity formula
mol/L
how to do titration
you have to use the acid/base that you know the most about for the first step. take the mL x (1L/1000ml) x (mol of 1stmL/1L)x (molar ratio; wanted/have) = mol of wanted
