Physics

posted by on .

How many atoms of hydrogen are in 220g of hydrogen peroxide (H2O2)?

This is what I did so far:

the molecular weight of H2O2 = 2*1 +2*16 =34

therefore, there are 220/34 moles of the molecule = 6.47 moles, so there are 6.47xAvogadro's number of molecules

there are 2 H atoms per molecule, so multiply 2x6.47x(6.02e^23) which is 7.591084947e^11
but for some reason it is wrong

• Physics - ,

I bet it is.
2*6.47*6.02E23 is nowhere near anything times E11.
Goodness. You are off by a factor of at least 1E12

• Physics - ,

Now, I'm getting 4870.270527 when I insert these values (2)*(6.470)*(6.02e^23)...is there any another way that i can insert theses into the calculator?

• Physics - ,

paste this into the google search window:

2*6.470*6.02E23

You need to learn how to be friends with your calc.

• Physics - ,

Sorry again to be pain in the neck...but this is what i got 2 * 6.47000 * 6.02E23 = 7.78988 × 1024...it is still wrong...this is driving me crazy

• Physics - ,

All I see is that the number of significant digits needs to be reduced, I would go to two, but the units need to be specified (grams). Did the idiot computer expect kilograms?

• Physics - ,

yes, it does. I tired all the combination but IT DOESN'T WORK. I am about to give up on this problem

• Physics - ,

If it expects kilograms, then 7.8E21kg

• Physics - ,

wait one sec:

2*6.47*6.02E23 NOT
2*6.47/6.02E23 Should be this.
divide molmass by avagradro's number to get mass of one molecule.

• Physics - ,

(2 * 6.47000) / 6.02E23 = 2.14950166 × 10-23...oh my god it is still wrong...