Question

2 NO + O2 -> 2 NO2

How many molecules of NO will react with 25.7 g O2

Answer 1

First find the how many moles of oxygen there are

Answer 2

You need to calculate the amount of moles 25.7 grams takes in O2.

that would be given mass/formula mass

formula mass of o2=32 grams (roughly)

Answer 3

remember, moles is found by dividing the number of grams by the molar mass

Answer 4

There are two mole of oxygen in the reactant sixe

Answer 5

Side*

Answer 6

Common confusion, that is one mole of oxygen

One mole of O2

2 moles of o2 would be 2O2

Answer 7

Oh, so O2 is counted as one mole

Answer 8

yes

Answer 9

32 g makes up that mole

Answer 10

That's just the molar ratio though. To find the actual moles of oxygen you need to divide the grams (25.7) by the molar mass (32 g/mol)

Answer 11

Yep, and take whatever number you get from that ^ and multiply that by the amount of moles of NO given in your equation..in this case (2)

Answer 12

It will be approximately 0.71388

Answer 13

So multiply that just by the number 2?

Answer 14

i think it should be 0.803 mol

Answer 15

yes, then multiply that by 2 because of the molar ratio

Answer 16

Yeah ^, I think you had a bad calculation Jamal.

Answer 17

Oh, yup. So multiply the 25.7 grams by the molar mass of one O2

Answer 18

Divide*

Answer 19

yes

Answer 20

25.7/32

Answer 21

0.803 times 2 is 1.606

Answer 22

Great so now we have the number of moles NO needed to react with 25.7 g of O2

Answer 23

Now we need to convert from moles to molecules

Answer 24

Do you know how to do that?

Answer 25

Mole to molecules is by using Avogadros number,

Answer 26

That's right, well done

Answer 27

So it would be 1.606 times (6.022 x 10^23)

Answer 28

yep

Answer 29

So it would be 9.671332 to the 23rd

Answer 30

That's right

Answer 31

Thanks!