I will help with the calculation and I will give a quick description of how to do it. You will need to make the list.
How many mols NaOH will you need? That's M x L = 0.25 x 0.500 L = 0.125.
How many grams NaOH is that? g = mols x molar mass = ?
Now weigh out that many grams of NaOH, transfer completely to a 500 mL volumetric flask, add some distilled or deionized water, swirl until all of the NaOH is dissolved, add more pure water to the mark on the volumetric flask, stopper, mix thoroughly, label.
Let me add something the problem didn't address. You should be aware that the solution you make up will NOT be 0.25 M even though you may have been very accurate in weighing and mixing. Why? Because NaOH absorbs H2O and CO2 from the air; therefore, your weighing a mixture of NaOH and Na2CO3 and H2O when you weigh out that mass of NaOH we calculated above. Also, let me add that when you transfer the solid NaOH you weigh to the volumetric flask there will be some NaOH that sticks to the container. So when I say transfer the solid you must do so quantitatively and not just dump from one container to another. So you will need a balance, a jar of NaOH, a container for the NaOH, a funnel, a wash bottle, distilled water, etc etc.
Imagine that you have been asked to prepare 500mL of a 0.25 mol/L solution of sodium hydroxide, NaOH.
a. Make a list of all of the materials and equipment you will require.
b. Describe how you will prepare this solution. Include any calculations that you will perform.
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