Question

When I have something like: Al(OH)3
would I set it up like this: 26.982(15.999+1.008)*3?

Answer 1

what are you trying to do?

Answer 2

mole to grams conversions

the question is: How many moles are in 98.3 grams of aluminum hydroxide, Al(OH)3

Answer 3

ah

Answer 4

how many moles of \(\sf Al(OH)_3 \) do you have?

Answer 5

thats the question; it only gave grams for me to find that.

Answer 6

you only have one mole

Answer 7

if you do not see a number before the name of the compound or molecule then it means there is only one mole.

Answer 8

\(\sf \huge x~ mole_{Al(OH)_3} \times \frac{grams_{Al(OH)_3}}{1 ~ mole_{Al(OH)_3}} = \)

Answer 9

do you see how the mole unit for a particular thing is canceled out algebraically?

Answer 10

\(\large a \times \huge \frac{b}{a} = b\)

Answer 11

yeah I see where it would be cancelled out. I just need to know how to find the molecular weight of the aluminum hydroxide.

Answer 12

whatever unit you're trying to convert out of, you need to divide by itself

Answer 13

molecular weight follows the conservation of mass
so if you see Al it means there is 1 Al in there
if you see \(\sf (OH)_3\) it means that there are 3 O's and 3 H's; the subscripts tell you how many there are for whatever each element that is enclosed in parenthesis

Answer 14

usually when there's 1, we do not write it out. it is just like saying a mole of something - it is implicit that the word "a" denotes 1

Answer 15

you're going to add all the weights of each elements in that molecule/compound

Answer 16

\(\sf \large Al(OH)_3 = [1 \times (weight_{Al})] + [3 \times (weight_{O}+weight_{H})] \)

Answer 17

get it?

Answer 18

so the answer is 78.003 correct?

Answer 19

I don't know the individual atomic mass units of each elements, that is something you need to reference to a periodic table.

Answer 20

its in the top

Answer 21

then start adding and multiplying

Answer 22

okay well thank you so much for you're help!!

Answer 23

@hwyl what about when it says: Ca3(PO3)2

Answer 24

Ca: \(3 \times \sf Ca \)
P: \(2 \times \sf P \)
O: \(2 \times 3 \sf ~ O \)