Question 2 of 3 Incorrect General Chemistry 4th Editiop University Science Books

Question

Question 2 of 3 Incorrect General Chemistry 4th Editiop University Science Books presented by Sapling Learning Rock Ga Prior to their phaseout in the 1980s, chemicals containing lead were commonly added to gasoline as anti-knocking agents. A 4.619 g sample of one such additive containing only lead, carbon, and hydrogen was burned in an oxygen rich environment. The products of the combustion were 5.027 g of CO2g and 2.572 g of H20(g). Insert subscripts below to appropriately display the empirical formula of the gasoline additive: C8H20Pbl

Explanation / Answer

Determination of empirical formula

moles C = 5.027 g/44 g/mol = 0.114 mol

mass C in sample = 0.114 x 12 = 1.371 g

moles H = 2 x 2.572 g/18 g/mol = 0.286 mol

mass H in sample = 0.286 x 2 = 0.572 g

mass Pb in sample = 4.619 - (0.114 + 0.286) = 2.676 g

moles Pb = 2.676 g/207.2 g/mol = 0.013 mol

Divide by smallest number

C = 0.114/0.013 = C = 8

H = 0.286/0.013 = 22

Pb = 0.013/0.013 = 1

empirical formula becomes = C8H22Pb

formulas used,

moles = grams/molar mass

grams = moles x molar mass

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