Question

If 14.3 moles of H2O2 is decomposed, how many grams of oxygen gas are produced? Show ALL your work to get full credit.

Answer 1

This is really a question for the chemistry section, but as you've already posted it here...

any thoughts on how to approach this?

Answer 2

I just realized I posted it in the Chem, sorry! :/ but no, not at all. I can't grasp the concept one bit....

Answer 3

if you decompose 1 mole of \(H_2O_2\), how many moles of oxygen result?

Answer 4

and how much mass does one of those moles of oxygen have?

Answer 5

2?

Answer 6

I don't know :/

Answer 7

okay, 2 is the right answer for the number of moles of oxygen.

Answer 8

Ok

Answer 9

the nifty thing about moles is that 1 mole of something has mass of whatever the atomic mass of 1 atom/molecule/whatever, in grams. So if you are talking about hydrogen, for example, which has an atomic mass of just a hair over 1, 1 mole of hydrogen atoms has a mass of just a hair over 1 gram

Answer 10

so, look up the atomic mass of oxygen in your periodic table, what do you get?

Answer 11

Okay, so how would I put that into an equation?

Answer 12

15.99

Answer 13

let's understand the concept first before worrying about the equation.

yes, my table says 15.9994 grams for 1 mole of oxygen atoms.

so, we know how many moles of oxygen (14.3), and we know the mass of 1 mole of oxygen, how might we find the mass of 14.3 moles of oxygen?

Answer 14

\[\text{mass} = \frac{\text{grams}}{\text{mole}} * \text{moles}\]

Answer 15

Uh, would we use division?

Answer 16

I just gave you the schematic... you know grams/mole (atomic mass), and you know moles (number of moles of oxygen)...

Answer 17

If I tell you that 1 pound of dog kibble costs $3.99, and I want you to buy 2 pounds, how would you find the cost?

Answer 18

unit price * number of units, right? exactly the same deal here.

\[\text{mass of oxygen} = \frac{15.9994\text{ grams oxygen}}{1\text{ mole oxygen}} * 14.3\text{ moles oxygen}\]\[\text{mass of oxygen} = \frac{15.9994\text{ grams oxygen}}{1\cancel{\text{ mole oxygen}}} * 14.3\cancel{\text{ moles oxygen}}\]\[\text{mass of oxygen} =15.9994\text{ grams oxygen} * 14.3 = \]

Answer 19

but I've deliberately made a mistake here...do you see what it is?

Answer 20

hint: didn't we decide that each mole of hydrogen peroxide decomposed into 2 moles of oxygen?