Ratios and Proportions?

Im stuck with this 1 question. I've had 3 people show me in 3 different ways with all the same answer but I still can't figure it out.

9 atoms of carbon combine with 8 atoms hydrogen and with 4 atoms of oxygen to form one molecule of Asprin

a)How many atoms of carbon combine with 16 atoms of oxygen?

b)How many molecules of Asprin form with 16 atoms of oxygen?

If you could please specific as possible with the answer and in detail, I'd greatly appreciate it.

somethin_fierce2007-05-24T10:43:16Z

Favorite Answer

all ratios such as this are answered the same way and its easiest to think about it with a simple example

hopefully you woul agree that 1/2 = 2/4

setting it up like that you can also say 1 x 4 = 2 x 2 by cross multiplication. its a simple algebraeic principle. if you need to remove the denominator of one side, simple multiply both sides by it. then multiply both sides by the denominator of the other side.

algebraically written it looks like this:

a/b = c/d
a = bc/d (ex 1 = 2x2/4)
b = ad/c (ex 2 = 1x4/2)
c = ad/b (ex 2 = 1x4/2)
d = bc/a (ex 4 = 2x2/1)

for your specific question:

a) 36
b)4

source: basic math

someone2007-05-24T19:06:39Z

imagine carbon:hydrogen:oxygen = 9:8:4
asked carbon and oxygen?
9:4=carbon:16
multiply the two outer numbers in both sides of the equation
9*16
multiply the two inner numbers in both sides of the equation
4 * carbon
then the products of these two are equal
so:
9*16 = 4 * carbon
144 = 4 * carbon ---- divide both sides by 4
144/4 = (4/4) *(carbon)
36 = carbon
------------------------------------------

*multiply the outer numbers (9*16) = 144
divide by (144/4) = 36