Question

При восстановлении алюминием оксида хрома Cr203 массой 15,2 г образовалось 9 г хрома.Рассчитайте выход хрома(в %) от теоретически возможного.Заранее спасибо!)

Answer 1

Cr2O3+2Al=2Cr+Al2O3

1) n(al)=15.2/27=0,563 моль

2) n(Cr)=n(Al)=0,563 моль

3) масса теор. (Cr)=0,563*52=29,276г

4) масса пр. (Cr)= 9 г по условию

5) выход=m пр/m теор* 100%=9/29,276*100=30,7%

Answer 2

Calculation of Chromium Yield

To calculate the yield of chromium (Cr) from the reaction of aluminum with chromium oxide (Cr2O3), we need to determine the theoretical yield and the actual yield. The yield of chromium is expressed as a percentage of the theoretical yield.

Given: - Mass of chromium oxide (Cr2O3) = 15.2 g - Mass of chromium (Cr) obtained = 9 g

To calculate the theoretical yield of chromium, we need to determine the stoichiometry of the reaction. From the balanced chemical equation, we can see that the molar ratio between chromium oxide (Cr2O3) and chromium (Cr) is 1:2.

Therefore, the theoretical yield of chromium can be calculated as follows:

1. Calculate the molar mass of chromium oxide (Cr2O3): - Molar mass of Cr = 52 g/mol - Molar mass of O = 16 g/mol - Molar mass of Cr2O3 = (2 * molar mass of Cr) + (3 * molar mass of O) = (2 * 52 g/mol) + (3 * 16 g/mol) = 152 g/mol

2. Calculate the number of moles of chromium oxide (Cr2O3): - Moles of Cr2O3 = Mass of Cr2O3 / Molar mass of Cr2O3 = 15.2 g / 152 g/mol = 0.1 mol

3. Calculate the theoretical yield of chromium (Cr): - Moles of Cr = 2 * Moles of Cr2O3 = 2 * 0.1 mol = 0.2 mol - Mass of Cr = Moles of Cr * Molar mass of Cr = 0.2 mol * 52 g/mol = 10.4 g

Now, we can calculate the yield of chromium as a percentage of the theoretical yield:

- Yield of chromium = (Actual yield of chromium / Theoretical yield of chromium) * 100% - Yield of chromium = (9 g / 10.4 g) * 100% = 86.54%

Therefore, the yield of chromium from the reaction is approximately 86.54% of the theoretical yield.