
Robert S. answered 03/01/21
Dr Bob Loves Science (especially chemistry and math)
Hello, Anoymoose,
We need to start with a balanced equation:
1N2 + 3Cl2 = 2NCl3
Now let's convert the 50.0 grams of NCl3 to moles by dividing by the molar mass of NCl3 (120.4g/mole). I get 0.415 moles NCl3. Since we only get 60% yield, we need to dividie the moles NCl3 by 0.60, to account for the loss. That means we need to plan to make 0.692 moles of NCl3, undoubtedly due to the clumsiness of the lab technician. The balanced equation tells us we need 1 mole of N2 for every 2 moles of NCl3 (a mole ratio of 1/2). So we need 1/2 of 0.692 moles, or 0.346 moles of N2. Multiply by nitrogen's molar mass of 28 (N2) to find grams N2 required. That looks VERY close to 9.70 grams. (It is).
Bob