A $25.0 \mathrm{~mL}$ sample containing nickel ions $(\mathrm{Ni} 2+)$ is treated with excess sodium hydroxide $(\mathrm{NaOH})$ solution, and the resulting precipitate is filtered and ignited to form nickel (II) oxide (NiO). If the mass of the obtained $\mathrm{NiO}$ is $0.325 \mathrm{~g}$, calculate the concentration of nickel ions in the original sample.

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∻Solution∻ ‖ 1 ⋮ **Write the balanced chemical equation**: The reaction between $\mathrm{Ni}^{2+}$ ions and $\mathrm{NaOH}$ leads to the formation of $\mathrm{Ni(OH)_2}$, which upon heating decomposes to form $\mathrm{NiO}$ and $\mathrm{H_2O}$. The balanced chemical equations are: $\mathrm{Ni}^{2+} + 2\mathrm{NaOH} ightarrow \mathrm{Ni(OH)_2} \downarrow$ and $\mathrm{Ni(OH)_2} ightarrow \mathrm{NiO} + \mathrm{H_2O}$. ‖ ‖ 2 ⋮ **Calculate moles of $\mathrm{NiO}$**: Use the molar mass of $\mathrm{NiO}$ to find the moles of $\mathrm{NiO}$ produced. The molar mass of $\mathrm{NiO}$ is approximately $58.69 \mathrm{~g/mol}$. The moles of $\mathrm{NiO}$ are calculated by the formula: $ ext{moles} = \frac{ ext{mass}}{ ext{molar mass}}$. Thus, $ ext{moles of NiO} = \frac{0.325 \mathrm{~g}}{58.69 \mathrm{~g/mol}}$. ‖ ‖ 3 ⋮ **Relate moles of $\mathrm{NiO}$ to moles of $\mathrm{Ni}^{2+}$**: From the balanced chemical equation, each mole of $\mathrm{NiO}$ comes from one mole of $\mathrm{Ni}^{2+}$. Therefore, the moles of $\mathrm{Ni}^{2+}$ in the original sample are equal to the moles of $\mathrm{NiO}$. ‖ ‖ 4 ⋮ **Calculate concentration of $\mathrm{Ni}^{2+}$ ions**: The concentration of $\mathrm{Ni}^{2+}$ ions in the original sample is calculated using the formula: $ ext{concentration} = \frac{ ext{moles of solute}}{ ext{volume of solution in liters}}$. Convert the volume from mL to L by dividing by 1000. Thus, $ ext{concentration of Ni}^{2+} = \frac{ ext{moles of Ni}^{2+}}{0.0250 \mathrm{~L}}$. ‖ ∻Answer∻ ⚹ [Insert final answer here] ⚹ ∻Key Concept∻ ⚹ Stoichiometry and molar mass are used to relate the mass of a compound to the amount of substance and to calculate the concentration of a solution. ⚹ ∻Explanation∻ ⚹ The concentration of nickel ions in the original sample is determined by calculating the moles of $\mathrm{NiO}$ produced and using stoichiometry to relate it back to the moles of $\mathrm{Ni}^{2+}$, followed by calculating the concentration with the volume of the sample. ⚹◊What is the chemical equation representing the reaction between nickel ions and sodium hydroxide to form nickel (II) oxide?⍭ Generate me a similar question◊

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