Write a balanced equation for the reaction between aqueous magnesium nitrate and aqueous potassium hydroxide to form solid magnesium hydroxide and aqueous potassium nitrate.
The correct answer and explanation is:
The balanced chemical equation for the reaction between aqueous magnesium nitrate (Mg(NO₃)₂) and aqueous potassium hydroxide (KOH) to form solid magnesium hydroxide (Mg(OH)₂) and aqueous potassium nitrate (KNO₃) is: Mg(NO₃)₂ (aq)+2KOH (aq)→Mg(OH)₂ (s)+2KNO₃ (aq)\text{Mg(NO₃)₂ (aq)} + 2\text{KOH (aq)} \rightarrow \text{Mg(OH)₂ (s)} + 2\text{KNO₃ (aq)}
Explanation:
- Identifying the Reactants and Products:
- Magnesium nitrate (Mg(NO₃)₂) is a soluble salt, meaning it dissociates in water into magnesium ions (Mg²⁺) and nitrate ions (NO₃⁻).
- Potassium hydroxide (KOH) is a strong base, also soluble in water, and dissociates into potassium ions (K⁺) and hydroxide ions (OH⁻).
- Magnesium hydroxide (Mg(OH)₂) is only slightly soluble in water and forms a precipitate when the reaction takes place.
- Potassium nitrate (KNO₃) is a soluble salt, and it dissociates in water into potassium ions (K⁺) and nitrate ions (NO₃⁻).
- Writing the Ionic Equation:
In solution, the ions involved are:- Magnesium nitrate dissociates into Mg²⁺ and 2NO₃⁻.
- Potassium hydroxide dissociates into K⁺ and OH⁻.
The magnesium hydroxide formed is insoluble and will precipitate as a solid, while potassium nitrate remains dissolved in solution as K⁺ and NO₃⁻.
- Balancing the Equation:
- The magnesium ion (Mg²⁺) from magnesium nitrate combines with two hydroxide ions (OH⁻) to form magnesium hydroxide (Mg(OH)₂), which precipitates out of solution.
- For every mole of magnesium nitrate, two moles of potassium hydroxide are needed to supply enough hydroxide ions (OH⁻) for the formation of magnesium hydroxide.
- Final Balanced Equation:
- Since there are two potassium ions (K⁺) from two KOH molecules and two nitrate ions (NO₃⁻) from one magnesium nitrate molecule, the equation is balanced as follows:
In conclusion, the equation is properly balanced with 1 magnesium atom, 2 potassium atoms, 2 nitrate ions, and 2 hydroxide ions on both sides of the equation.