Combustion analysis of 1.00g of testosterone yields 2.90g of CO2 and .875g H2O. What are the mass percents of carbon, hydrogen, and oxygen in testosterone?
If 7.35g of chromium reacts directly with oxygen to form 10.74g of a metal oxide, what is the simplest formula of the metal oxide? name the oxide.
If 7.35g of chromium reacts directly with oxygen to form 10.74g of a metal oxide, what is the simplest formula of the metal oxide? name the oxide.
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(2.90 g CO2) / (44.0096 g/mol) x (1/1) x (12.0108 g C/mol) / 1.00 g = 0.791 = 79.1% C
(0.875 g H2O) / (18.0153 g/mol) x (2/1) x (1.0079 g H/mol) / 1.00 g = 0.0979 = 9.79% H
100% - 79.1% C - 9.79% H = 0.111 = 11.1% O
(7.35 g Cr) / (51.9962 g Cr/mol) = 0.141356 mol Cr
(10.74 g - 7.35 g) / (15.9994 g O/mol) = 0.211883 mol O
Divide by the smaller number of moles:
(0.141356 mol Cr) / 0.141356 = 1.000
(0.211883 mol O) / 0.141356 = 1.499
In order for these molar ratios to come close to integers, they must be multiplied by 2. So multiply each by 2 then round to the nearest whole number to find the empirical formula:
Cr2O3
which is chromium (III) oxide.
(0.875 g H2O) / (18.0153 g/mol) x (2/1) x (1.0079 g H/mol) / 1.00 g = 0.0979 = 9.79% H
100% - 79.1% C - 9.79% H = 0.111 = 11.1% O
(7.35 g Cr) / (51.9962 g Cr/mol) = 0.141356 mol Cr
(10.74 g - 7.35 g) / (15.9994 g O/mol) = 0.211883 mol O
Divide by the smaller number of moles:
(0.141356 mol Cr) / 0.141356 = 1.000
(0.211883 mol O) / 0.141356 = 1.499
In order for these molar ratios to come close to integers, they must be multiplied by 2. So multiply each by 2 then round to the nearest whole number to find the empirical formula:
Cr2O3
which is chromium (III) oxide.