exam 1 review

Question 1

addition and subtraction sig fig rules

Answer 1

least amount of decimals

Question 2

multiplication and division sig fig rules

Answer 2

least amount of sig figs

Question 3

how to figure out # of protons, neutrons , electrons, charge

Answer 3

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

Question 4

what do the letters a and z represent when it comes to the periodic table and protons neutrons and electrons

Answer 4

A= the number of protons and neutrons
Z= the number of protons

Question 5

how to determine empirical formula

Answer 5

change percents to grams, divide by their molar mass, then divide them all by the smallest answer

Question 6

how do you complete chemical reactions

Answer 6

outter-> outter, inner-> inner, then balance

Question 7

how to write total ionic and net ionic equations

Answer 7

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

Question 8

be able to balance reactions

Answer 8

.

Question 9

how to find theoretical yield

Answer 9

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

Question 10

how to find percent yield

Answer 10

actual yield divided by theoretical yield x 100

Question 11

how to find atomic mass

Answer 11

multiply atomic mass by isotopic abundance and add them all up

Question 12

how to find isotopic abundance

Answer 12

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

Question 13

how to calculate moles given grams

Answer 13

take the given grams and divide by molar mass (number of periodic table)

Question 14

how to calculate atoms given grams

Answer 14

take given grams, divide by molar mass, multiple by avogadros number

Question 15

how to calculate grams given mols

Answer 15

multiply given moles by molar mass

Question 16

how to calculate mass percent

Answer 16

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

Question 17

how to find mass of a compound given the mass of one element in the compound

Answer 17

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

Question 18

How to find formula units

Answer 18

multiply grams by avagadros number

Question 19

how to find molecular formula given percents of each element

Answer 19

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

Question 20

how to write combustion reactions

Answer 20

compound + O2 -> CO2 + H2O

Question 21

how to do stoichiometry

Answer 21

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

Question 22

what are the oxidation number rules

Answer 22

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

Question 23

oxidation and reduction definition and rules

Answer 23

oxidation: loss of electrons O.N. goes up
reduction: gain of electrons O.N. goes down
oxidized= reducing agent
reduced= oxidizing agent

Question 24

scientific notation rules

Answer 24

big-small = positive 
small-big= negative

Question 25

Celsius to K

Answer 25

k= c+ 273.15

Question 26

f to celsius

Answer 26

c= (f-32) x (5/9)

Question 27

density formula

Answer 27

d= m/v

Question 28

molarity formula

Answer 28

mol/L

Question 29

how to do titration

Answer 29

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