How many oxygen atoms are there in 7.00 g of sodium dichromate,Na₂Cr₂O₇?

Question

Quizplus · Accepted Answer

First, calculate the molar mass of sodium dichromate (Na2Cr2O7): Na (22.99 g/mol) * 2 + Cr (51.996 g/mol) * 2 + O (16.00 g/mol) * 7 = 261.97 g/mol. Then, find the number of moles in 7.00 g of Na2Cr2O7: 7.00 g / 261.97 g/mol = 0.0267 mol. Since there are 7 oxygen atoms per formula unit, the total number of oxygen atoms is 0.0267 mol * 7 * Avogadro's number (6.022 × 10^23 atoms/mol) = 1.13 × 10^23 atoms.

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