Question

How would I Calculate the number of molecules present in each of the following samples. 6.55 g of carbon monoxide. ___________molecules

Answer 1

Someone please help! :(

Answer 2

@samjordon

Answer 3

You first need to find the molecular mass of carbon dioxide, You can do this by adding the atomic weights of carbon and oxygen.

Once you do that you can convert to moles by dividing the sample mass by the molecular mass.

Answer 4

never mind... It took me a while but finally got it! thanks for the help

Answer 5

ok great

Answer 6

i need help with another D:

Answer 7

can you help me with that??

Answer 8

sure

Answer 9

k its Calculate the mass of 1.45 ✕ 1025 molecules of SO3. Use a molar mass with at least as many significant figures as the data given.

Answer 10

ummmm

Answer 11

mass of 1.45 x 10^25

Answer 12

ok, so you first need to calculate the molecular mass of SO3. Can you do that?

Answer 13

yeah the mass of SO3 is 80.06

Answer 14

Ok, so now that you have that we do some dimensional analysis.

The problem gives us number of molecules, but we want the mass (grams).
In stochiometry problems, the best way to convert between different values is to convert to moles first, once have the number of moles solving for anything else is fairly trivial.

Answer 15

okay

Answer 16

So yo convert to moles, we know that 1 mole of any substance is equivalent to 6.022 x 10^23 units. In this case its equivalent to 6.022 x 10^23 molecules.

Answer 17

to*

Answer 18

okay

Answer 19

So since we know that, we just follow the math:

\[\frac{1.45 * 10^{25} molecules}{} * \frac{1 mole}{6.022 * 10^{23} molecules } = ?\]

The molcule units cancel out and we are left with the number of moles. I left the arithmetic as an exercise for you to solve, but do you understand up to this point?

Answer 20

yeah i do i see where i made my mistake... haha i put the 6.02 x 10^23 ontop :/

Answer 21

good, so you know how to solve it from here? you just take moles and convert to mass using the molecular mass from before.

Answer 22

wait what? lol im so dumb i got confused again :(

Answer 23

yeah sorry , I'm switching between 2 questions.

Ok, so now that you have the number of moles of SO3, you setup another fraction.

\[\frac{?\,moles\,SO3}{}*\frac{80.06\,g\,SO3}{1\,mole\,SO3} = ??\,g\,SO3\]

where ? is what you just solved for, and the ?? is the result. I just setup the 2nd fraction to eliminate the units I don't want on the bottom and the desired unit on top.

Answer 24

haha your good

Answer 25

Thanks

Answer 26

i still got it wrong :(

Answer 27

so i solved the first equation on top and got 2.41. I then used that number to plug in the ? on the second equation and did 2.41 x 80.06. The final answer was than 192, but it wasnt correct

Answer 28

hold on let me check your work

Answer 29

I got 24.08 moles for the first step. I would check the math again.

Answer 30

oh woah okay

Answer 31

Did you get it?

Answer 32

yeah! Thank you so much! you helped :)

Answer 33

no problem