What is the minimum mass of magnetite (Fe, O2), a iron ore, from which 120. g of pure iron could be extracted? Be sure your answer has a unit symbol, if necessary, and is rounded to 3 significant digits.

166 g

Explanation:

Step 1: Write the reaction for the obtaining of Fe from magnetite

Fe₃O₄ ⇒ 3 Fe + 2 O₂

Step 2: Calculate the moles corresponding to 120 g of Fe

The molar mass of Fe is 55.85 g/mol.

120 g × (1 mol/55.85 g) = 2.15 mol

Step 3: Calculate the moles of Fe₃O₄ required to produce 2.15 moles of Fe

The molar ratio of Fe₃O₄ to Fe is 1:3. The moles of Fe₃O₄ required are 1/3 × 2.15 mol = 0.717 mol

Step 4: Calculate the mass corresponding to 0.717 moles of Fe₃O₄

The molar mass of Fe₃O₄ is 231.53 g/mol.

0.717 mol × 231.53 g/mol = 166 g

tracks, burrows, eggshells, nests, tooth marks, or gastroliths

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"