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# OCR A2 Physics - Need some help with moles Watch

1. I need some help with a moles question, I just can't seem to understand moles. If you could please explain these questions for me and how I can get the answers.

Thanks
Reda
2. To calculate number of moles simply divide mass given to you by the mass number. So in the question number of moles is equal to 12/12. Hence number of moles is equal to 1. Use Avogadro's constant to calculate number of atoms or particles (same thing really). Avogadro stated that the number of atoms in a substance is the same once you know the number of moles. 1 mole of any substance has 6.02×10 to the power of 23.

So in the question given to you 1 mole of carbon (which you calculated ) must have Avogadro's number.

The thing about moles is that everyone gets hung about the definition of the mole. It is irrelevant. It is simply a unit. Chemists and Physicists need to use it as they work with infentismally small amounts.

All I can say is that the more you practice mole calculations the easier they become.
3. (Original post by Reda2)
I need some help with a moles question, I just can't seem to understand moles. If you could please explain these questions for me and how I can get the answers.

Thanks
Reda
This question doesn't seem legit, where did you get it from?

the mass of 1 mole of carbon is ~12 grams, you're probably just going to confuse yourself by practicing nonsense questions.

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1 mole of anything is 6,02 x 1023 of those things... it's a very large number so it's usually used for very small things like atoms or molecules.
6.02 x 1023 is called Avagadro's number

1 mole of carbon atoms is 6,02 x 1023 carbon atoms so if you know the mass of a sample of carbon you can work out the number of moles of atoms it contains quite simply, ti's 12 g per mole... but it's not acceptable to make up values for the mass of a mole of carbon as the author of this question has done.

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