Question

The question is How many grams of carbon (C) are present in a sample of 2.5 × 1024 atoms C?
The answer is 49.9g, but I don't know why this is the answer. Can you help me to understand?

Answer 1

what do you know about avogadro's number and a mole of things?

Answer 2

To do these kind of questions I always like to remember a sort of formula that helps you not only do this question, but other ones like it too.

So, what you need to do for this firstly is find the moles. That is because you can convert the amount of molecules into moles but not into grams straight away (finding the moles can then lead you onto finding the grams of a substance).

You can remember how to convert the amount of molecules of a substance into moles using this triangle of equations (molecules/atoms mean the same thing):

To find what you need, all you have to do is use your finger to cover up what you need, and then do what the triangle tells you to do, for example if I wanted the moles of a substance but I had the no. of molecules, I would cover up the moles on the triangle with my finger, and then do: no. of molecules/avagadros number, and it will give you your answer.

So now you have the no. of moles, we have another triangle that can help us work out grams from no. of moles:

So, you can use this triangle then to work out the amount in grams of carbon, by covering up 'moles' on the triangle, and then doing what it says on the triangle.

After all this, you should come up with the correct answer! (Which is hopefully 49.9g)

I hope this helped, good luck :)
If you need any help feel free to ask

Answer 3

Super helpful! Thank you so much!

Answer 4

No problem! Glad I could help :)