A solution was prepared by dissolving 5.76 g of KCl. MgCl2 ·6 H2 O(277.85 g / mol) in sufficie

step 1 If we have a solution that is prepared by taking 20 grams KCL and dissolving it in 100 millilite

A solution was prepared by dissolving 5.76 g of KCl. MgCl2...

A solution was prepared by dissolving $5.76 \mathrm{~g}$ of $\mathrm{KCl}$. $\mathrm{MgCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}(277.85 \mathrm{~g} / \mathrm{mol})$ in sufficient water to give $2.000 \mathrm{~L}$. Calculate (a) the molar analytical concentration of $\mathrm{KCl} \cdot \mathrm{MgCl}_{2}$ in this solution. (b) the molar concentration of $\mathrm{Mg}^{2+}$. (c) the molar concentration of $\mathrm{Cl}^{-}$. (d) the weight/volume percentage of $\mathrm{KCl} \cdot \mathrm{MgCl}_{2}$. $6 \mathrm{H}_{2} \mathrm{O}$. (e) the number of millimoles of $\mathrm{Cl}^{-}$in $25.0 \mathrm{~mL}$ of this solution. (f) $\mathrm{ppm} \mathrm{K}{ }^{+}$. (g) $\mathrm{pMg}$ for the solution. (h) $\mathrm{pCl}$ for the solution.

A solution was prepared by dissolving $5.76 \mathrm{~g}$ of $\mathrm{KCl}$. $\mathrm{MgCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}(277.85 \mathrm{~g} / \mathrm{mol})$ in sufficient water to give $2.000 \mathrm{~L}$. Calculate
(a) the molar analytical concentration of $\mathrm{KCl} \cdot \mathrm{MgCl}_{2}$ in this solution.
(b) the molar concentration of $\mathrm{Mg}^{2+}$.
(c) the molar concentration of $\mathrm{Cl}^{-}$.
(d) the weight/volume percentage of $\mathrm{KCl} \cdot \mathrm{MgCl}_{2}$. $6 \mathrm{H}_{2} \mathrm{O}$.
(e) the number of millimoles of $\mathrm{Cl}^{-}$in $25.0 \mathrm{~mL}$ of this solution.
(f) $\mathrm{ppm} \mathrm{K}{ }^{+}$.
(g) $\mathrm{pMg}$ for the solution.
(h) $\mathrm{pCl}$ for the solution.

Key Concepts

Weight/Volume Percent Concentration

Weight/volume percentage is a concentration unit that expresses the mass of solute in grams present in a specified volume of solution, usually 100 mL. This measurement is important in scenarios where the percentage composition is needed for preparing solutions and in comparing solution strengths.

Ion Dissociation in Aqueous Solutions

When salts dissolve in water, they often dissociate into their constituent ions. This concept involves using the stoichiometry of the salt to determine the molar ratios of the ions produced. It is key for calculating the concentrations of individual ions, like Mg2+ and Cl–, based on the amount of the dissolved compound.

Parts Per Million (ppm) Concentration

PPM concentration is a way to express very dilute concentrations, defined as the mass of solute per one million parts of solution. It is particularly useful when dealing with trace amounts of a component, like a specific ion, in a large volume of solution.

Molarity and Molar Concentration

This concept involves determining the number of moles of a solute by dividing its mass by its molar mass, and then expressing its quantity per unit volume of solution (in liters). Molarity is a fundamental measure of concentration in chemistry and is used to connect the amount of substance with the volume of the solution in which it is dissolved.

Stoichiometry of Hydrated Salts

Hydrated salts contain water molecules as part of their crystalline structure, meaning that when calculating the molar mass of a compound, the mass of the water of hydration must be included. Understanding this is essential to accurately determine the number of moles when a compound is given in its hydrated form.

Logarithmic p-Form Expression for Ion Concentration

The use of p-notation (such as pMg or pCl) involves taking the negative logarithm (base 10) of the molar concentration of an ion. This logarithmic scale provides a more manageable number when dealing with very small concentrations and is analogous to the pH scale used in acid–base chemistry.

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