What is the minimum mass of Mg(NO3)2 that must be added to 1.00 L of a 0.210 M HF solution to begin precipitation of MgF2(s)? For MgF2, Ksp = 7.4 x 10°, and Ka for HF = 7.2 x 104.
Ionic Equilibrium
Chemical equilibrium and ionic equilibrium are two major concepts in chemistry. Ionic equilibrium deals with the equilibrium involved in an ionization process while chemical equilibrium deals with the equilibrium during a chemical change. Ionic equilibrium is established between the ions and unionized species in a system. Understanding the concept of ionic equilibrium is very important to answer the questions related to certain chemical reactions in chemistry.
Arrhenius Acid
Arrhenius acid act as a good electrolyte as it dissociates to its respective ions in the aqueous solutions. Keeping it similar to the general acid properties, Arrhenius acid also neutralizes bases and turns litmus paper into red.
Bronsted Lowry Base In Inorganic Chemistry
Bronsted-Lowry base in inorganic chemistry is any chemical substance that can accept a proton from the other chemical substance it is reacting with.
![**Question:**
What is the minimum mass of Mg(NO₃)₂ that must be added to 1.00 L of a 0.210 M HF solution to begin precipitation of MgF₂(s)? For MgF₂, Ksp = 7.4 × 10⁻⁹, and Ka for HF = 7.2 × 10⁻⁴.
**Explanation:**
This problem involves determining the minimum mass of magnesium nitrate (Mg(NO₃)₂) needed to be added to a given volume and concentration of hydrofluoric acid (HF) solution in order to start the precipitation of magnesium fluoride (MgF₂).
### Steps to Solve:
1. **Determine the solubility product constant (Ksp):**
- For magnesium fluoride (MgF₂), the solubility product constant, Ksp, is given as 7.4 × 10⁻⁹.
- The dissolution reaction of MgF₂ in water can be written as:
\[ \text{MgF}_2 (s) \leftrightarrow \text{Mg}^{2+} (aq) + 2 \text{F}^{-} (aq) \]
- Therefore, the Ksp expression is:
\[ K_{sp} = [\text{Mg}^{2+}][\text{F}^{-}]^2 \]
2. **Determine the ion product (Q):**
- We need to find the concentration of fluoride ions ([F⁻]) in the solution before Mg²⁺ ions are added. Assuming complete dissociation of HF, and recognizing the weak acid context:
\[ \text{HF (aq)} \leftrightarrow \text{H}^+ (aq) + \text{F}^- (aq) \]
- The acid dissociation constant is given by:
\[ Ka = 7.2 \times 10^{-4} \]
3. **Calculate the fluoride ion concentration:**
- Since HF is a weak acid, its degree of dissociation can be calculated using the initial concentration and the Ka value:
\[ Ka = \frac{[\text{H}^+][\text{F}^-]}{[\text{HF}]} \]
- Assume the degree of dissociation is small, the initial concentration of HF ([HF]₀](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fcab27ebe-ca52-4065-95ad-a0b64c44780e%2F8da9354b-f775-411b-be08-ba3aeb0edf6e%2Fn983hs_processed.jpeg&w=3840&q=75)
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