Question

Cr(NO3)3;.найти w(N)

Answer 1

М(Cr(NO3)3) = 238 г/моль

М(N)=14 г/моль

w(N)=  3 × 14 г/моль : 238 г/моль = 42г/моль : 238 г/моль = 0,1765 = 17,65%

Answer 2

To find the molar mass of a compound, we need to sum up the molar masses of all the individual elements present in the compound. Let's calculate the molar mass of Cr(NO3)3:

1. Chromium (Cr) molar mass: 51.996 g/mol (you can find this value in the periodic table).
2. Nitrogen (N) molar mass: 14.007 g/mol (also from the periodic table).
3. Oxygen (O) molar mass: 16.00 g/mol (from the periodic table).

Now, we have three nitrogen atoms in the formula.

Molar mass of Cr(NO3)3 = Molar mass of Cr + 3 * (Molar mass of N) + 9 * (Molar mass of O)

Molar mass of Cr(NO3)3 = 51.996 g/mol + 3 * 14.007 g/mol + 9 * 16.00 g/mol

Molar mass of Cr(NO3)3 = 51.996 g/mol + 42.021 g/mol + 144.00 g/mol

Molar mass of Cr(NO3)3 = 237.017 g/mol

Now, to find the weight of nitrogen (w(N)) in one mole of Cr(NO3)3, we need to calculate the fraction of nitrogen's molar mass in the total molar mass:

w(N) = (3 * Molar mass of N) / Molar mass of Cr(NO3)3 w(N) = (3 * 14.007 g/mol) / 237.017 g/mol w(N) = 42.021 g/mol / 237.017 g/mol w(N) ≈ 0.1775 or 17.75%

Therefore, the weight of nitrogen (w(N)) in one mole of Cr(NO3)3 is approximately 17.75%.