3.2 calculations w/ moles Flashcards
What is a mole?
1 mole = 6.022x10^23
* avagadros #
* he often drops that last 2
If i had a mole of donuts it would mean i had 6.022x10^23 donuts
* such a large # that were really not going to use this # outside of chemistry
I have 1 mole of carbon atoms, how mnay carbon atoms does that mean I have?
6.022x10^23 carbon atoms
if you look at a typical atom of carbon 12, if you divide that by 12, were going to call that the atomic mass unit
* so 1/12 of a carbon 12 atom is 1amu
6.02x10^23 a.m.u = 1g
* so this is out connection between grams and avagadros #
1 C atom = 12.011 a.m.u - you can call this the automic weight
* 12 is found on periodic table
1 mole of C = 12.011g - molar mass (talking about a mole of carbons instead of a single one)
* because 1 amu = 1g
a.m.u = automic mass unit = daltons
With molecular compounds we introduce a term called molecular weight (doesnt work w/ ionic compounds because they dont stick togther the same way)
* you just add up the atoms in the formula that are in each individual molecule
Molecular wt:
* CO2
* C = 12.011
* O = 15.999x2
* (12.011 x 1) + (15.999 x 2) = 44.01 a.m.u
again 1 a.m.u = ~what 1 proton or 1 neutron weighs
NaCl doesnt have a molecular weight because its not a molecular compound
* its an ionic compound
* Instead they have whats called the formula weight (techniqually this can be applied to any compound) - but its the weight of 1 formula unit
* So even though in NaCl theres tons and tons of them bond together (like shown below) not individual distincit molecules (that exist in molecular compounds)
* so in formula weight we essentially just look at the formula and add up the weight of that
* NaCl formula weight= (22.99 x 1) + (35.45 x 1) = 58.44 amus
We can also talk about an entire mole
molecular weight oc CO2 = 44.01 amu (essentailly just the weight of all the protons and neutrons in the molecule)
1 mole of CO2 molecules has a molar mass of 44.01g/mole
* This is talking about an entire mole of CO2’s weight
NaCl formula weight = 58.44 amu
* Molar mass = 58.44g/mole - this is talking about an entire mole of NaCl’s weight
1 mole = 6.022x10^23 particles (atoms, molecules, etc)
* Units of molar mass: g/mole - so how much does it weight per 6.022x10^23 parts
To find molar mass of water
* Hydrogen has a molar mass = 1.008 g/mol
* Oxygen has a molar mass 16.00 g/mol
H2O = 2.016 + 16.00 g/mol
1 atom of hydrogen = 1.008 amu
1 mole of hydrogen atoms weights (6.022 x 10^23) 1.008 grams
molar mass is always the connection between grams and moles
1 mole of carbon
* how many carbon atoms do I have = 6.022x10^23 carbon atoms in a mole
* How much does it weight? - well 1 mole of carbon is whats on peridoic table - so theres 1 mole of every single element in grams on the periodic table
* 1 mole of carbon = 12.011g/mol
How many carbon atoms are in 3 mole of carbon?
Basically we can convert moles to individual atoms by knowing 1m carbon = 6.022x10^23 carbon atoms.
shown below
* theres a moles atoms conversion
* basically moles is just a count of anything
so avagadros numbers connects us from # of moles to indiivudal atoms
Connection through moles and grams is always through the molar mass
EX: How much does 3 moles of carbon weigh?
Well this is found on the periodic table
1 mole carbon = 12.011
So theres a connection between moles and atoms/molecules through avagardos number (1 mole = 6.022x10^23)
Theres a connection between moles and grams through molar mass (found on the periodic table)
You have a 300g sample of CaCO3
* How many moles do you have
* # of O atoms in the sample
* Grams of carbon
Important
* ratios are the hard part
Missed this one
so you have to create the ratio of 5 atoms to 1 molecules (which are equivilent measurements because there are 5 atoms in a molecule)
