Question

Calculate the number of moles of helium that contains 3.25 x 10^21 atoms.

Answer 1

Without numbers, can you figure this out.
Always start with given value
\[\frac{ atoms}{ 1}\times \frac{ mol }{ atoms }\]

Answer 2

3.25 x 10^ 21 atom x (1mol/6.022 x 10 23 atom)

Answer 3

Right?

Answer 4

\[3.25 x 10^{21} atom x \frac{ 1 mol }{ 6.022 x 10^{23} atom }\]

Answer 5

Yes, that is right.
Sorry I was helping someone.

Answer 6

And I get .539687811

Answer 7

Units would be in moles of helium.

Answer 8

So .539687811 mol He?

Answer 9

It has to be 3 sf since the given value only has 3.
Remember that your answer has a 0 in the front.
It does not count as a sf.

Answer 10

.540 mol He?

Answer 11

Yes
Nice rounding!

Answer 12

Thanks

Answer 13

No problem!

Answer 14

It's saying the answer is wrong. I did it right...Right?

Answer 15

I did not do the calculations since you got the right conversion.
You did the calculation.
Do the calculation again.

Answer 16

I think you put 3.25*10^23 instead of 3.25*10^21

Answer 17

I did it again and got the same answer.

Answer 18

Write down what you calculate then.

Answer 19

\[3.25\times10^{21} atomtimes \frac{ 1mol }{ 6.022 \times10^{23 } }atom\]

Answer 20

3.25 x 10^21 atom x

Answer 21

Dont forget parentheses. (3.25*10^21)/(6.022*10^23)

Answer 22

Right

Answer 23

Got .00540 mol He

Answer 24

So what did you do wrong earlier?

Answer 25

Forgot parentheses or wrong exponent?

Answer 26

I put it in the calculator without parentheses

Answer 27

Another way is multiply 3.25*10^21 and lets called that x
then multiply 6.023*10^23 and call that y.
Then just do x/y if you arent comfortable with parentheses.