Problem 143
A compound subjected to analysis was found to have the following composition by weight: \(69.96 \%\) carbon (atomic weight \(=12.0 \mathrm{~g} / \mathrm{mole}), 7.83 \%\) hydrogen (atomic weight \(=1.01 \% \mathrm{~g} /\) mole \()\), and \(22.21 \%\) oxygen (atomic weight \(=\) \(16.0 \mathrm{~g} / \mathrm{mole})\). If the molecular weight of this compound is 360 \(\mathrm{g} /\) mole, what is its molecular formula?
Problem 144
The most common constituent of gasoline is iso-octane. It is a hydrocarbon, composed by weight of \(84.12 \%\) carbon, and \(15.88 \%\) hydrogen. Given that it contains \(5.27 \times 10^{21}\) molecules per gram, what is its molecular formula?
Problem 145
Calculate the percentage composition of aluminum sulfate, \(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\)
Problem 146
Two thirds of the atoms in a molecule of water \(\left(\mathrm{H}_{2} \mathrm{O}\right)\) are hydrogen. What percentage of the weight of a water molecule is the weight of the two hydrogen atoms? The atomic weight of hydrogen is \(1.008 \mathrm{~g} /\) mole and of oxygen is \(16.00 \mathrm{~g} / \mathrm{mole} .\)
Problem 147
Calculate the percent composition by weight of ether \(\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{O}\)
Problem 148
calculate the percent weight of each element in magnesium chloride, \(\mathrm{MgCl}_{2}\).
Problem 149
Using the Periodic Table of Elements, find the following for sodium dihydrogen phosphate, \(\mathrm{NaH}_{2} \mathrm{PO}_{4}:\) (a) formula weight, (b) percent composition of oxygen, (c) weight in grams of \(2.7\) moles, and (d) percentage composition of oxygen in \(2.7\) moles.
Problem 150
Calculate the weight of iron in 350 pounds of \(\mathrm{Fe}_{2} \mathrm{O}_{3}\). First, calculate the percent of iron in the compound.
Problem 151
What is the elemental percent composition (by weight) of a mixture that contains \(20.0 \mathrm{~g}\) of \(\mathrm{KAl}\left(\mathrm{SO}_{4}\right)_{2}\) and \(60.0\) of \(\mathrm{K}_{2} \mathrm{SO}_{4} ?\)
Problem 152
When a piece of magnesium ribbon weighing \(0.32 \mathrm{~g}\) is burned in oxygen, the resultant oxide weighs \(0.53 \mathrm{~g}\). What is the percentage composition of the oxide?
