Final answer:
To determine the percentage composition of Be in beryl, calculate the molar mass of Be and the molar mass of the entire compound. Divide the molar mass of Be by the molar mass of beryl and multiply by 100 to get the percentage composition.
Step-by-step explanation:
The percentage composition of Be (beryllium) in beryl (Be3Al2Si6O18) can be determined by calculating the molar mass of Be in the compound and dividing it by the molar mass of the entire compound. The molar mass of Be is 9.01 g/mol, and the molar mass of beryl can be calculated by adding up the molar masses of all the elements in the compound.
Molar mass of beryl = (3 x molar mass of Be) + (2 x molar mass of Al) + (6 x molar mass of Si) + (18 x molar mass of O)
After calculating the molar mass of beryl, divide the molar mass of Be by the molar mass of beryl and multiply by 100 to get the percentage composition.