determine the amounts of solute and solvent needed to prepare the following solutions.

2.0 M aqueous NaCl solution
1.0 m aqueous KCl solution
25% by mass aqueous MgCl2 solution

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To determine the amounts of solute and solvent needed to prepare the given solutions, we need to know the desired volume of the solution. Assuming we want to prepare 1 liter (1000 mL) of each solution, I will explain the steps for each one:

1. 2.0 M aqueous NaCl solution:
A 2.0 M solution means that we have 2 moles of NaCl dissolved in 1 liter (1000 mL) of solution. To determine the amount of NaCl needed, we need to calculate the molar mass of NaCl, which is 58.44 g/mol. Therefore, we need 2 moles * 58.44 g/mol = 116.88 grams of NaCl. To prepare 1 liter of the solution, we will dissolve 116.88 grams of NaCl in enough water to make the final volume 1000 mL.

2. 1.0 M aqueous KCl solution:
Similar to the previous example, we have 1.0 mole of KCl dissolved in 1 liter (1000 mL) of solution. The molar mass of KCl is 74.55 g/mol. So, we need 1 mole * 74.55 g/mol = 74.55 grams of KCl. Dissolve 74.55 grams of KCl in enough water to make the final volume 1000 mL.

3. 25% by mass aqueous MgCl2 solution:
A 25% by mass solution means that we have 25 grams of solute per 100 grams of solution (25 grams of solute / 100 grams of solution). To determine the amount of MgCl2 needed, we need to set up a proportion between grams of solute and grams of solution. Let's assume we want to prepare 100 grams of solution. Then, the amount of MgCl2 needed would be (25 grams MgCl2 / 100 grams solution) * 100 grams = 25 grams of MgCl2. Dissolve 25 grams of MgCl2 in enough water to make the final volume 100 mL.