91Ó°ÊÓ

Write the formula for the following hydrates. \begin{equation} \begin{array}{l}{\text { a. nickel(II) chloride hexahydrate }} \\ {\text { b. cobalt(II) chloride hexahydrate }} \\ {\text { c. magnesium carbonate pentahydrate }} \\ {\text { d. sodium sulfate decahydrate }}\end{array} \end{equation}

A compound contains 6.0 \(\mathrm{g}\) of carbon and 1.0 \(\mathrm{g}\) of hydrogen, and has a molar mass of 42.0 \(\mathrm{g} / \mathrm{mol}\) . What are the compound's percent composition, empirical formula, and molecular formula?

Which of these compounds has the greatest percent of oxygen by mass: \(\mathrm{TiO}_{2}, \mathrm{Fe}_{2} \mathrm{O}_{3},\) or \(\mathrm{Al}_{2} \mathrm{O}_{3} ?\)

Mothballs Naphthalene, commonly found in mothballs, is composed of 93.7\(\%\) carbon and 6.3\(\%\) hydrogen. The molar mass of naphthalene is 128 \(\mathrm{g} / \mathrm{mol}\) . Determine the empirical and molecular formulas for naphthalene.

Write balanced equations for each reaction. (Chapter 9) \begin{equation} \begin{array}{l}{\text { a. Magnesium metal and water combine to form solid }} \\\ {\text { magnesium hydroxide and hydrogen gas. }} \\ {\text { b. Dinitrogen tetroxide gas decomposes into nitrogen }} \\ {\text { dioxide gas. }} \\ {\text { c. Aqueous solutions of sulfuric acid and potassium }} \\\ {\text { hydroxide undergo a double-replacement reaction. }}\end{array} \end{equation}

Luminol Crime-scene investigators luminol and detervisualize blood residue. Research luminol and determine its chemical formula and percent composition.