12. Why might a chemist add a buffer to a solution? The buffer can keep the pH stable when small amounts of acid or base are added. The buffer reacts with the acid or base in solution to form a useful product. The buffer changes color to indicate the pH of the solution. The buffer can magnify the changes to pH caused by adding small amounts of acid or base.

What is the formula for the ionic compound? formula: $\square $

Calculate the solubility at $25^{\circ }C$ of $CaF_{2}$ in pure water and in a 0.0110M NaF solution. You'll find $K_{sp}$ data in the ALEKS Data tab. Round both of your answers to 2 significant digits. solubility in pure water: $\square \frac {g}{L}$ solubility in 0.0110 M NaF solution: $\square \frac {g}{L}$

Question 13 What is the formula for phosphoric acid? HBr

Balance this equation by typing the correct coefficients in the blanks. $\square C_{2}H_{5}OH+\square O_{2}\rightarrow \square CO_{2}+\square H_{2}O$

3. For the balanced equation shown below, if the reaction of 91.39 grams of $C_{3}H_{6}$ produces a $81.36\% $ yield, how many grams of $CO_{2}$ would be produced? $2C_{3}H_{6}+9O_{2}\Longrightarrow 6CO_{2}+6H_{2}O$

30 Consider the following reaction at $25^{\circ }C$ $3Ni(s)+N_{2}(g)+3H_{2}O(g)\rightarrow 3NiO(s)+2NH_{3}(g)$

An atomic cation with a charge of $+3$ has the following electron configuration: $[He]2s^{2}2p^{6}$ What is the chemical symbol for the ion? How many electrons does the ion have? How many 2s electrons are in the ion? $\square $ $\square $ $\square $

Identify the spectator ions for the reaction between calcium nitrate and sodium sulfate.The balanced molecular equation is $Ca(NO_{3})_{2}(aq)+Na_{2}SO_{4}(aq)\rightarrow CaSO_{4}(s)+2NaNO_{3}(aq)$ $Na^{+}$ and $NO_{3}^{-}$ $Ca^{2+}$ and $NO_{3}^{-}$ $Na^{+}$ and $SO_{4}^{2-}$ $Ca^{2+}$ and $SO_{4}^{2-}$

Drag each tile to the correct location on the table. Classify the properties based on whether they describe metals or nonmetals. \begin{array}{|c|c|c|} \hline\ \begin{array}{l}\ They\ are\ good\ conductors\ \\ of\ heat\ and\ electricity. \end{array} & \begin{array}{l}\ They\ are\ brittle\ and\ \\ break\ into\ sharp\ pieces. \end{array} & \begin{array}{l}\ They\ are\ flexible\ and\ can\ \\ be\ made\ into\ wires. \end{array} \\ \hline \begin{array}{l}\ They\ are\ mostly\ solids\ \\ at\ room\ temperature. \end{array} & \begin{array}{l}\ They\ are\ poor\ conductors\ \\ of\ heat\ and\ electricity. \end{array} & \begin{array}{l}\ They\ are\ solids,\ liquids,\ or\ \\ gases\ at\ room\ temperature. \end{array} \\ \hline \end{array} \begin{array}{|l|l|} \hline\ Metals\ &\ Nonmetals\ \\ \hline\ &\ \\ &\ \\ &\ \\ \hline \end{array}

Use the References to access important values if needed for this question. The molar solubility of chromium(III)hydroxide in a water solution is $\square $ M.