Molar Mass Calculations


okay as you know chemical compounds and
their formulas come in a huge variety there are almost unlimited number of them in this video
I’m gonna show you how to calculate the molar mass for
various chemical compounds using their formulas
now let’s go through it quickly what molar mass is. Molar mass is simply the mass
one mole just like it says molar mass mass of one mole alright. A mole of course is a number of
particles. it’s the metric unit expresses the number particles that you
have. one mole is equal to 6.02 times 10 to the 23
particles 23rd particles. of course that’s a huge
number almost unimaginable but it is just what
it is it’s one mole the 6.02 times to the 23rd. you know a
dozen is 12 and now you know that one mole 6.02 times 10 to the 23rd okay let’s go
through and just look at a couple molar masses
for actual elements before we do compounds we have
carbon aluminum we look at our periodic table
we have this is the carbon block I have that the atomic number is
six C is the symbol here’s the name and
this number as it says on here is the average atomic mass but that is also the molar mass. for
aluminum the molar masses 26.98 for carbon
is is 12.01 so I’m just gonna write that down and I write to right down like this. I just
don’t write down 12.01. I put one mole is equal to 12.01 grams and I can do the same thing for aluminum one mole is equal to 26.98 grams okay I got those numbers right of my period
table if I want them all aluminum if I want 6.02 times ten to the 23rd atoms of aluminum I just would have to take my balance weigh out 26.98 grams of aluminum okay now let’s do some compounds now they’re
gonna the have a compound have hydrogen sulfur oxygen different numbers up each element in our chemical formula so I think is a
process I’m steps that you can do that will help
you to be successful if you follow these steps: the first step of course is to write
down what elements you have in this case we have hydrogen we had
sulfur and we have oxygen that is step one the
next step is to write down how many atoms each
element are hydrogen there’s two I put two times sulfur there’s one so I put one times oxygen there’s four so I put for times step 2: now for Step three a am going to write down the molar masses the more massive
hydrogen of course is 1.01 games right of my periodic table grams
sulfur is 30 to point 0 7 grams and oxygen is of course 16 point 0 0 grams those the molar masses right from
the periodic table now I’m gonna multiply across and then
I’m going to add them up so two times 1.01 is course to point all to and program there this is one times thirty two sons going right
down 30 to point although 7 grams and for oxygens is me 64 wanted 0 0 grams so I’m gonna just do that and then add
them up and I end up with the molar mass
sulfuric acid is 98 point 0 9 grand I’m gonna write that down like
this one mall is equal 298 point although 9 grams that is the more mass for sulphuric acid alright we followed
the steps course the last step was to write down
the answer right let’s do another one okay once again
we’re just going to follow the same steps I think we’ve all those steps we should
be successful an week course here we have lead nitrate so
we have some lead we have some nitrogen and we have some
oxygen in this case we have one lead we have two nitrogens and we have 6 oxygens this too is outside the parenthesises
these applies to everything that inside we have two nitrates each nitrate has one nitrogen so we have two of those and each nitrate has three oxygens so we have six of those I just think it was distributing this
through two times one two times three is six alright so lead has a molar mass 207.02 grams point I know its here 207.02 grams nitrogen is 14.o1 grams and oxygen is still 16.00 grams now and going to multiply these through which is stays as 207 obviously this becomes 28.02 grams and 16 times 6 is 96 grams and I’m going to add them all up and I get that the molar mass lead
nitrate is 331.04 grams and that means that my answer is that
one mole of lead nitrate has a mass of 331.04 grams good that is the answer to that question erase that it’s going to last one we’re
going to do one more home as you can see we have calcium
chloride opps this should we should be a lower case
two but this needs to be a subscript to but we have calcium chloride with two waters on it we call that calcium chloride
dihydride we have some calcium we have some chlorine we have some
hydrogen and we have some oxygen. how many a each? one calcium, two chlorines, two waters each water has two
hydrogens so we have four we have two waters each
water has one oxygen so we have two oxygens and then we can
write down the more masses more mass calcium is 40.08 grams, chlorine is 35.45 grams hydrogen is still 1.01 grams and oxygen is still 16.00 grams okay the next step we’re going to
multiply these through well just one calcium so this is 40.08 grams this is see 35 times two is 70.90 grams, four times this is 4.04 not 4.01 and this last one of course 16 times 2 is simply 32.00 grams. so I add them all up I get 100 and 47 point 02 grams that means at the molar mass
of calcium chloride dihydride is the equal to 147.02 grams. that is the answer okay so you can see I follow the steps I
wrote down the elements I wrote down how many wrote down the
molar masses multiplied across and then add them up I
got my answer and I wrote my answer like that. okay
think that’s pretty straightforward all those steps follow that process and
you gobi successful okay thank you very much hope that was helpful you get any
questions or comments you can leave them in the comment section below thank you.

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