anonymous one year ago If you were asked to convert 4.2 X 10^22 atoms of aluminum to moles, which of the following should you use for the conversion?

1. imqwerty

$\frac{ 4.2 \times 10^{22}}{ N_{A} }$ N_{A} is the avagadro number

2. imqwerty

yea sure :)

3. imqwerty

1mole of any substance has 6.022 x 10^23 particles of it

4. imqwerty

so 1 mole of Al has 6.022 x 10^23 atoms

5. Mertsj

well which one of those is true? is 6.023x10^23 atoms of Al equal to 13 moles Al

6. imqwerty

now if 1 mole has 6.022 x 10^23 atom then how many mole will have 4.2 x 10^22 atoms :)

7. imqwerty

can u calculate how many moles will have 1 atom?

8. imqwerty

well just because it has that bad number 26.891... we can't say its wrng we have to give proper reasoning ok we know that 1mole has 6.022 x 10^23 particles we need to find how many moles will have 1 particle so 1st answer this- 6 bags have 3 chocolates how many bags will have 1 chocolate?

9. wolf1728

What's with the mass of aluminum? The origianl question just want number of moles.

10. imqwerty

ur saying B is correct cause it has got mass/ nvm its ok :)

11. wolf1728

But the original question was just "how many moles is 4.2 x 10^22 atoms".

12. wolf1728

There are 6.023 x 10^23 atoms per mole. You have 4.2 x 10^22 atoms. 4.2 x 10^22 * 1 mole/6.023 x 10^23 atoms

13. imqwerty

yes

14. wolf1728

Or number 4 in your list

15. wolf1728

sure

16. wolf1728

2.03 X 10^24 atoms * 1 mole/6.023 x 10^23

17. wolf1728

Look carefully at my answer. You don't multiply both numbers.

18. imqwerty

number of moles = no of atoms /avagadro number :)

19. wolf1728

I made a graphic which shows the calculation more clearly:

20. imqwerty

yes :D

21. wolf1728

B it is!!

22. wolf1728

okay 1 more question.

23. imqwerty

np B)

24. imqwerty

moles=mass/molar mass molar mass of silver=108

25. imqwerty

yea correct :D

26. wolf1728

Remember to learn how to set it up correctly. What if you set it up as 107.9/68.3?

27. wolf1728

Yes you set it up the right way 68.3/107.9 but you will have to see why.

28. wolf1728

The important thing is if you know the correct way to set up the answer because I'm assuming you will be tested on this, right?

29. wolf1728

So then you will definitely have to learn how to set up the answer.

30. wolf1728

Well imqwerty and myself looked at the answers and we're sure they are correct.

31. wolf1728

Atomic mass of copper = 63.55 meaning there are 6.023 x 10^23 atoms for every 63.55 grams of copper. We need to know atoms in 68.7 grams of copper: 68.7 * 6.023 x 10^23 atoms / 63.55 grams copper = 6.511 x 10^23 atoms which is C which is your answer

32. wolf1728

Moles in 125 g of NI atomic mass Ni = 58.71 grams per mole 125 grams * 1 mole / 58.71 grams = 2.129 moles B (which is your answer)

33. imqwerty

#( 1mole of silver=108gm=6.022x10^23 particles $\frac{ 108\times 5.8 \times 10^{23} }{ 6.022 \times 10^{23}}=mass of (5.8 \times 10^{23})particles$

34. imqwerty

^#9

35. wolf1728

I'm working on number 8

36. wolf1728

It seems to me you just want correct answers as opposed to HOW to set up the answers. Question 8 - your answer is wrong. What is the mass of 25 atoms of mercury? (your answer)

37. imqwerty

yes sofia :) thas correct

38. wolf1728

39. imqwerty

np :) sofia can u tell how did u find out the mass

40. imqwerty

nvm :) tell ur method

41. wolf1728

Yes it is either B or C for #8

42. imqwerty

yes

43. imqwerty

ok :)

44. imqwerty

yes :D

45. imqwerty

np (:

46. wolf1728

Did you figure out #8 yet?

47. wolf1728

Yes it is C - very good!