[poll id=”10″]
ANSWER – A 26.5%
The molecular formula of potassium dichromate is K₂Cr₂O₇. To find the percent composition, calculate the weight of the entire molecule:
(2 x 39 g/mol) + (2 x 52 g/mol) + (7 x 16 g/mol) = 294 g/mol
Then divide the weight of the potassium in the molecule by the entire molecular weight:
(2 x 39 g/mol) / 294 g/mol = 0.265
Multiply x100 to produce the percentage value: 0.265 x 100 = 26.5%