How many Cr atoms in 78.82 g potassium dichromate?

[Banaticus]

How many Cr atoms in 78.82 g potassium dichromate?
Potassium dichromate is $$\textrm{K}_{2}\textrm{Cr}_{2}\textrm{O}_{7}$$.

I said:

The molecular mass of potassium dichromate is:
39.1*2+52*2+16*7=294.2

So, in 78.82 g potassium dichromate, there are 78.82/294.2= 0.2680 moles of potassium dichromate. Each mole of potassium dichromate has $$6.022~x~10^{23}$$ molecules, each with 2 chromium atoms. So, in one mole, there are $$1.204~×~10^{24}$$ chromium atoms. So, in .2680 moles, there are $$.2680(1.2044~×~10^{24})~=~3.228~×~10^{23}$$, correct?

As a sidenote, it appears that LaTeX graphical formulas can't be seen in the preview mode -- the only way to check them is to post the message then edit the message if they're wrong? Also, where can I find a better LaTeX tutorial than https://www.physicsforums.com/misc/howtolatex.pdf which just doesn't give enough information? Ah, https://www.physicsforums.com/showthread.php?t=9021 has some pretty good information, but I still don't seem to be doing my LaTeX correctly.

 

[dmoravec]

Yes, that looks good. And I don't currently know of any better LaTeX tutorial, I've just been learning it recently too and would also be interested in a more in depth tutorial.

 

[Blueshift5]

Your calculations are correct. In 78.82 g of potassium dichromate, there are 3.228 × 10^23 chromium atoms.

Regarding your questions about LaTeX, it is true that the preview mode does not show LaTeX graphical formulas. The only way to check them is to post the message and then edit if needed. As for finding a better LaTeX tutorial, there are many resources available online, such as tutorials and forums where you can ask for help. Some popular ones include Overleaf, LaTeX Project, and TeX Stack Exchange.