How many grams of beryllium are in 147 g of mineral beryl?

The number of Beryllium that are in 147g of mineral Beryl is calculated as below

find the moles of mineral Beryl = mass / molar mass

molar mass beryl mineral (Be3Al2Si6O18) = (9x3) + (27x2) + (28 x6) + (16 x18) = 537

= 147g/537 g/mol = 0.274 moles of Be3Al2Si6O18

find the moles Be in Beryl mineral

that is 3 x 0.274=0.822 moles since there is 3 molecules of Be in beryl mineral

mass of Be is therefore = moles of Be x molar mass of Be

0.822moles x 9 g/mol = 7.4 g of Be