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When we talk about HCl dissociation, we're discussing how hydrochloric acid (HCl) breaks down into its ions in water. HCl is a strong acid, and when it dissolves, it splits completely into two ions: hydrogen ion (\(H^+\)) and chloride ion (\(Cl^-\)). This process is known as complete dissociation, meaning that almost all HCl molecules separate into ions in solution.

- **Ion Charges**: Both \(H^+\) and \(Cl^-\) have a charge of 1. So, in calculating the ionic strength of an HCl solution, we consider the contribution of each ion with their respective charges squared.- **Ionic Strength Formula**: Use the formula \( I = \frac{1}{2} \sum c_i z_i^2 \) where \(c_i\) and \(z_i\) are the concentration and charge of ion \(i\), respectively.

To find the ionic strength of a 0.0055 molal HCl solution, plug in the values to get \( I = \frac{1}{2} \times (0.0055 \times 1^2 + 0.0055 \times 1^2) = 0.0055 \). This reflects the concentration of ions and their charges in the solution.

Sodium bicarbonate (\(NaHCO_3\)) is a salt that dissociates in water. It breaks down into two ions: sodium ion (\(Na^+\)) and bicarbonate ion (\(HCO_3^-\)). Understanding the charges on these ions is key for addressing ionic strength.

- **Ion Characteristics**: The \(Na^+\) ion has a positive charge of 1, and the \(HCO_3^-\) ion has a negative charge of 1. Both are monovalent ions.- **Dissociation Process**: This dissociation results in equal amounts of each ion, as the process involves breaking down the NaHCO3 entirely.

To calculate the ionic strength of a 0.075 molal NaHCO3 solution, use \( I = \frac{1}{2} \times (0.075 \times 1^2 + 0.075 \times 1^2) = 0.075 \). Each ion contributes equally, reflecting the full dissociation and ion distribution in solution.

The compound iron(II) nitrate, represented as \(Fe(NO_3)_2\), dissociates in water to form iron ions and nitrate ions. Specifically, it produces one iron(II) ion \(Fe^{2+}\) and two nitrate ions \(NO_3^-\).

- **Ion Charges**: The \(Fe^{2+}\) ion carries a charge of +2, while each \(NO_3^-\) ion has a charge of -1.- **Contribution to Ionic Strength**: The charge of the ions affects the ionic strength significantly. Each \(Fe^{2+}\) ion has a squared charge contribution of 4 due to its +2 charge, magnifying its impact on the ionic strength.

For a 0.0250 molal solution of \(Fe(NO_3)_2\), calculate as follows: \( I = \frac{1}{2} [(0.025 \times 2^2) + 2(0.025 \times 1^2)] = 0.075 \). The formula shows how both the concentration and the charge of ions determine the overall ionic strength.

Iron(III) nitrate, designated as \(Fe(NO_3)_3\), dissociates in water into iron and nitrate ions. This yields one iron(III) ion \(Fe^{3+}\) and three nitrate ions \(NO_3^-\).

- **Ion Charges**: The \(Fe^{3+}\) ion holds a triple positive charge (+3), while each nitrate ion holds a single negative charge (-1).- **Influence on Ionic Strength**: The high charge of \(Fe^{3+}\) greatly influences ionic strength because the contribution depends on charge squared (\(3^2 = 9\)). Nitrate's charges add up due to their count and impact the total ionic strength.

For a 0.0250 molal \(Fe(NO_3)_3\) solution, calculate: \( I = \frac{1}{2} [ 0.025 \times 3^2 + 3 \times 0.025 \times 1^2 ] = 0.15 \). This calculation clearly shows the significance of iron's higher charge in determining the ionic strength of the solution.