The most common source of copper (\rm Cu) is the mineral chalcopyrite (\rm CuFeS_2). How many kilograms of chalcopyrite must be mined to obtain 210.g of pure \rm Cu?

210 g x [(molar mass CuFeS2)/atomic mass] Cu and convert to kg.

To find the amount of chalcopyrite that must be mined to obtain 210 g of pure Cu, we need to use the molar mass of the two compounds and the stoichiometry of their reaction.

First, we calculate the molar mass of copper (Cu) and chalcopyrite (CuFeS2):
- Cu: Atomic mass of Cu = 63.55 g/mol
- CuFeS2: Atomic mass of Cu + Atomic mass of Fe + 2 x Atomic mass of S = 63.55 g/mol + 55.85 g/mol + 2 x 32.06 g/mol = 183.53 g/mol

Next, we use stoichiometry to relate the amount of Cu in chalcopyrite:
- Balanced Equation: 2 CuFeS2 -> 2 Cu + FeS2 (Assuming complete conversion)
- From the equation, we can see that 2 moles of CuFeS2 produce 2 moles of Cu.

Now we can set up the calculations:
1. Calculate the number of moles of Cu (n) using the equation:
n = mass / molar mass
n = 210 g / 63.55 g/mol = 3.306 mol

2. Use the stoichiometry of the reaction to determine the number of moles of CuFeS2 required:
From equation: 2 moles of CuFeS2 = 2 moles of Cu
Therefore, 1 mole of CuFeS2 = 1 mole of Cu
So, the number of moles of CuFeS2 = 3.306 mol

3. Finally, calculate the mass of chalcopyrite (CuFeS2):
Mass of CuFeS2 = moles x molar mass
Mass of CuFeS2 = 3.306 mol x 183.53 g/mol = 606.2 g

Therefore, approximately 606.2 grams (or 606.2 kg) of chalcopyrite must be mined to obtain 210 g of pure Cu.