select the correct answer.\nthe mineral benitoite is a gemstone for making jewelry. it has a molecular…

select the correct answer.\nthe mineral benitoite is a gemstone for making jewelry. it has a molecular weight of 413.44 grams/mole and a percent composition of 33.21% ba, 11.58% ti, 20.38% si, and 34.83% o. what is the molecular formula?\n\na. batisi₃o₉\nb. ba₂tisi₂o₃\nc. batisi₃o₆\nd. batisi₆o₉

select the correct answer.\nthe mineral benitoite is a gemstone for making jewelry. it has a molecular weight of 413.44 grams/mole and a percent composition of 33.21% ba, 11.58% ti, 20.38% si, and 34.83% o. what is the molecular formula?\n\na. batisi₃o₉\nb. ba₂tisi₂o₃\nc. batisi₃o₆\nd. batisi₆o₉

Answer

Explanation:

Step1: Calculate moles of each element

Assume 100 g of the compound. Then the masses of Ba, Ti, Si, and O are 33.21 g, 11.58 g, 20.38 g, and 34.83 g respectively. Moles of Ba: $n_{Ba}=\frac{33.21\ g}{137.33\ g/mol}\approx0.242\ mol$ Moles of Ti: $n_{Ti}=\frac{11.58\ g}{47.87\ g/mol}\approx0.242\ mol$ Moles of Si: $n_{Si}=\frac{20.38\ g}{28.09\ g/mol}\approx0.725\ mol$ Moles of O: $n_{O}=\frac{34.83\ g}{16.00\ g/mol}\approx2.177\ mol$

Step2: Find the mole - ratio

Divide each number of moles by the smallest number of moles (0.242 mol). Ratio of Ba: $\frac{0.242\ mol}{0.242\ mol}=1$ Ratio of Ti: $\frac{0.242\ mol}{0.242\ mol}=1$ Ratio of Si: $\frac{0.725\ mol}{0.242\ mol}\approx3$ Ratio of O: $\frac{2.177\ mol}{0.242\ mol}\approx9$

Answer:

A. $BaTiSi_{3}O_{9}$