Question

question 3 of 4 points possible: 1.00 in a certain compound of iron and oxygen, fe_xo_y, it is found that a sample of this compound weighing 6.285 g contains 4.396 g of fe. what is the formula of the oxide? select one: a. feo b. fe_2o c. feo_2 d. fe_2o_3

Explanation:

Step1: Calculate mass of oxygen

Mass of oxygen = Total mass of compound - Mass of iron. So, $m_O=6.285 - 4.396=1.889$ g.

Step2: Calculate moles of iron

Molar mass of Fe is approximately 55.85 g/mol. Moles of Fe, $n_{Fe}=\frac{4.396}{55.85}\approx0.0787$ mol.

Step3: Calculate moles of oxygen

Molar mass of O is approximately 16 g/mol. Moles of O, $n_O=\frac{1.889}{16}\approx0.118$ mol.

Step4: Find mole - ratio of Fe to O

Divide each number of moles by the smaller number of moles. $\frac{n_{Fe}}{n_{Fe}} = 1$, $\frac{n_O}{n_{Fe}}=\frac{0.118}{0.0787}\approx1.5$. Multiply by 2 to get whole - number ratio. The ratio of Fe to O is 2:3.

Answer:

d. Fe₂O₃