Write a detailed set of instructions for making two solutions: (1) 100.0 mL of 12-M NaOH from solid sodium hydroxide and (2) 1.00 L of 0.1 M NaOH from your first solution. You have in your lab: volumetric flasks marked to contain 100.0 mL and 1.000 L, a graduated cylinder, and a balance.

Molarity refers to the concentration of a solution, often described in moles of solute per liter of solution. The molarity equation, pivotal in chemistry, is expressed as M = moles/L. To calculate the moles required when preparing a desired volume of solution with a specific molarity, we must first understand the molar mass of the solute – in this case, sodium hydroxide (NaOH).
In our exercise, the goal is to make 100.0 mL of a 12 M NaOH solution. To determine the amount of NaOH needed, we follow these steps:

• Convert the volume from milliliters to liters, understanding that 1000 mL equals 1 L.
• Multiply the desired molarity by the volume in liters to find the moles of NaOH needed.
• Once we have the moles, we multiply by the molar mass of NaOH to convert moles to grams.

Such molarity calculations are essential for precise solution preparation, ensuring the concentration of the resultant mixture meets the experiment's requirements. Keep the units consistent throughout the process, and remember that accuracy in measurement is key to achieving the correct molarity.

In laboratories, volumetric flasks are used for preparing precise solution volumes. Recognizable by their pear shape and a long neck with a marked line, they ensure accurate measurement of liquids to a specific volume.
To use a volumetric flask correctly:

• Start by adding a portion of the solvent—it's usually distilled water—to dissolve the solute.
• Add the solid solute measured previously using a balance, and continue dissolving, often with the help of a stirring rod.
• Once the solute is fully dissolved, fill the flask with solvent up to the mark on the neck. The meniscus, or the curve seen at the top of the liquid, should just touch this line when you view it at eye level.
• Finally, invert the flask several times to mix the solution thoroughly, ensuring homogeneity.

Important Reminders:

Never fill the flask to the mark before dissolving the solute, as this can lead to an incorrect volume and thus an incorrect molarity. Furthermore, always make sure the final mix is homogeneous to ensure consistent concentration throughout the solution.

Serial dilution is a stepwise process of diluting a stock solution to lower concentrations, which is particularly useful when the final concentration required is much lower than the stock concentration.
The exercise involves diluting a 12 M NaOH solution to a 0.1 M solution. Using the dilution equation C1V1 = C2V2, we can determine the volume of the concentrated stock solution needed to achieve the desired concentration after dilution.

• C1 is the initial concentration (12 M).
• V1 is the volume of this concentrated solution we need to find.
• C2 is the final concentration desired (0.1 M).
• V2 is the total volume of the diluted solution (1.00 L).

Once V1 is calculated, that precise volume is taken from the stock solution and added to a volumetric flask of the final desired volume. The flask is then filled up to the mark with solvent to achieve the 0.1 M NaOH solution. Remember, proper mixing is essential in this step, too. Serial dilution is not only more efficient than making a new solution from scratch, but it's also a way to minimize waste and ensure accuracy in preparation.