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How to find moles of a particular element in a compund?
Ok, heres the question
How many atoms of oxygen are there in 882 g of K2Cr2O7?
Can someone please tell me the formula for finding moles of particular elements in a compund, and show me how they worked this question out? Thanks
1 Answer
- Anonymous1 decade agoFavorite Answer
No formula. In one mole of K2Cr2O7 there are 2 moles of K, 2 moles of Cr and 7moles of O
The molar mass of K2Cr2O7 is 294.19 g therefore you have
882g/294.19g/mole=2.99 moles K2Cr2O7 (Probably ok to call it 3)
You have 7 moles of O for each mole of K2Cr2O7 so you have 21 moles of O
1 mole contains 6.02 x 10^23 atoms (Avagadro's number)
7moles O x 6.022 x 10^23 atoms/mole = 4.2 x 10^24 atoms