the atomic mass of N is 14 u and that of Ca is 40 u. the proportion of n by mass in the compound Ca3N2 is what?
To find the proportion of nitrogen (N) by mass in the compound Ca3N2, we need to calculate the molar mass of the compound and then determine the proportion of nitrogen in that mass.
1. Start by finding the molar mass of Ca3N2.
- The atomic mass of calcium (Ca) is 40 u.
- The subscript 3 indicates that there are three calcium atoms, so the total mass of calcium is (40 u) x 3 = 120 u.
- The atomic mass of nitrogen (N) is 14 u.
- The subscript 2 indicates that there are two nitrogen atoms, so the total mass of nitrogen is (14 u) x 2 = 28 u.
- The molar mass of Ca3N2 is the sum of the masses of calcium and nitrogen, which is 120 u + 28 u = 148 u.
2. Calculate the proportion of nitrogen by mass:
- To find the proportion, divide the molar mass of nitrogen by the molar mass of Ca3N2 and multiply by 100 to get the percentage.
- (28 u / 148 u) x 100 = 18.92%
Therefore, the proportion of nitrogen by mass in the compound Ca3N2 is approximately 18.92%.