1. Determine the molar mass of chlorophyll C55H72MgN4O5:
C: 55 x 12.01 g/mol = 660.55 g/mol
H: 72 x 1.008 g/mol = 72.58 g/mol
Mg: 1 x 24.305 g/mol = 24.305 g/mol
N: 4 x 14.01 g/mol = 56.04 g/mol
O: 5 x 16.00 g/mol = 80.00 g/mol
Total molar mass = 660.55 + 72.58 + 24.305 + 56.04 + 80.00 = 893.48 g/mol
2. Calculate the mass of nitrogen in chlorophyll C55H72MgN4O5:
Mass of nitrogen = 4 x 14.01 g/mol = 56.04 g/mol
3. Calculate the percent nitrogen by mass:
% Nitrogen = (Mass of nitrogen / Total molar mass) x 100
% Nitrogen = (56.04 g/mol / 893.48 g/mol) x 100 = 6.28%
Therefore, the percent nitrogen by mass in chlorophyll C55H72MgN4O5 is approximately 6.28%.
