15) How many grams are in 2.3times 10^-4 moles of calcium phosphate, Ca_(3)(PO_(3))_(2) 16) How many moles are in 3.4times 10^-7 grams of silicon dioxide, SiO_(2)

15) To find the number of grams in moles of calcium phosphate, , we need to calculate the molar mass of the compound first.The molar mass of calcium phosphate is calculated by adding the molar masses of each element in the compound:- Calcium (Ca): 40.08 g/mol- Phosphorus (P): 30.97 g/mol- Oxygen (O): 16.00 g/molSo, the molar mass of calcium phosphate is: g/molNow, we can calculate the number of grams in moles of calcium phosphate: moles 310.18 g/mol = 0. gramsTherefore, there are 0.0714 grams in moles of calcium phosphate, .16) To find the number of moles in grams of silicon dioxide, , we need to calculate the molar mass of the compound first.The molar mass of silicon dioxide is calculated by adding the molar masses of each element in the compound:- Silicon (Si): 28.09 g/mol- Oxygen (O): 16.00 g/molSo, the molar mass of silicon dioxide is: g/molNow, we can calculate the number of moles in grams of silicon dioxide: moles = molesTherefore, there are moles in grams of silicon dioxide, .