Question

who could help me with stoichiometry?

Answer 1

I could.

Answer 2

Thanks! ok I will copy the question

Answer 3

C8H18 + O2 = CO2 + H2O

Answer 4

what volume of oxygen is needed to produce 13.5 liters of carbon dioxide?

Answer 5

Do you know how to balance equations?

Answer 6

yes, so wait a minute I will balance it

Answer 7

Please do. When you're done, post it here. It's kind of large though, just a warning.

Answer 8

ok, is 2 C8H18 + 25 O2 => 16 CO2 + 18 H2O

Answer 9

sorry I had some problems and I couldn't be in the class and I also speak spanish, and today I had the spring concert and tomorrow is my gradbash and EOC, that's my story heheh I hope you could explain it to me because I really want to understand, my teacher can't stay after school

Answer 10

Okay, well you know everything in that balanced equation are ratios. For every 2 C8H18 there are 25 O2 and so on.

Answer 11

so for every 4 C8H18 there are 50 O2?

Answer 12

just asking

Answer 13

Yes, exactly. You can adjust the values, as long as they still reduce to what they were all along. So if you had 4C8H18 and 50 O2, you'd also have to have 32 CO2 and 36 H2O on the other side.

Answer 14

ok I get it

Answer 15

They are MOLE ratios though. Not volume ratios.

Answer 16

so now I have to convert from liters to volume

Answer 17

ok, Moles not volume ratios

Answer 18

Liters is the volume. You'd convert the liters to moles.

Answer 19

but that ask about what volume of oxygen and they gave me liters of carbon dioxide.... or first I have to convert to moles?

Answer 20

First you have to convert the volume of CO2 to moles. Then you'd use the ratios to determine how many moles of O2 would make CO2. Then you would convert the amount of O2 moles to volume.

Answer 21

ok.... I think that I get it.... let me try

Answer 22

ok so I got 12.34 moles of O2

Answer 23

Remember, there is 25 moles of O2 for every 16 moles of CO2.

Answer 24

32.42 moles of O2?

Answer 25

\[\frac{ 13.5L }{ 1 } \times \frac{1 mol}{22.4L} = .602678571 mols CO2\]
And since there are 25 O2 moles for every 16 co2 moles
\[\frac{.602678571 mol CO2}{1} \times \frac{25 mol O2}{16 mol CO2} =0.941685267 mol O2\]
Now convert back to volume.
\[\frac{ 0.941685267mol O2 }{ 1 } \times \frac{22.4L}{1mol} = 21.0937499808L O2.\]
Since there were only 3 significant figures in the original measure up top in the question, we would be able to say that the answer is 21.1 L of O2.

Answer 26

WOOOW! I really appreciate your help! thanks! really thanks I'm reading now

Answer 27

You're welcome. :)

Answer 28

Ok, I have a question. I know you are super smart and super kind and cute ok, but after you multiply with the balnced equation so, 25/16, you don't have to multiply time Molar Mass new and divided by I mol? just asking because I really don't understand very well what I have on a little sheet

Answer 29

Well I mean it depends on what the questions are asking. If it asks for volume (or mass), you have to convert into volume (or mass) AFTER determining moles.

Answer 30

Ok, I get it, sometimes the questions is hard to understand well just because I just move here, and this is not my first language, sorry if I wrote something wrong

Answer 31

Thanks again!