Question

Find the amount of oxygen in 0.891 mol of Na2Cr2O7

Answer 1

Answer:

Explanation:

Step 1: Determine the molar mass of sodium dichromate:

MM (Na2Cr2O7)

= 2 x MW(Na) + 2 x MW(Cr) + 7 x MW(O)

= 2 x 22.990 g/mol + 2 x 51.996 g/mol + 7 x 15.998 g/mol

= 261.958 g/mol

Step 2: Use stoichiometry:

3.37 g Na2Cr2O7 x (1 mol Na2Cr2O7 / 261.958 g Na2Cr2O7) x (7 mol O / 1 mol Na2Cr2O7)

Step 3: Determine the answer for (a) via calculation the above.

# moles of Oxygen = ???

PART (B)

Take the number of moles of oxygen in part (a). Multiply the number of moles of oxygen by Avogadro's number.

??? moles of Oxygen x (6.022 x 1023 oxygen atoms / 1 mol Oxygen) = ??????