How many grams of sodium hydroxide (NaOH) are required to prepare 150.0 mL of a 5.0% w/v solution?

To determine the amount of sodium hydroxide (NaOH) needed to prepare a 150.0 mL solution at a concentration of 5.0% w/v, it's essential to understand how percentage solutions are calculated. A 5.0% w/v (weight/volume) solution means there are 5.0 grams of solute (in this case, NaOH) for every 100 mL of solution.

First, you need to calculate the grams of NaOH needed for 150.0 mL:

1. Calculate the amount of NaOH in grams for 100 mL:

• A 5.0% w/v solution contains 5.0 grams of NaOH in 100 mL.

2. Next, set up a proportion to find out the amount required for 150.0 mL:

• If 5.0 grams is to 100 mL, then X grams is to 150.0 mL (where X is the unknown amount of NaOH).

• This can be expressed mathematically as:

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\frac{5.0 , \text{g}}{100 , \text{mL}} = \frac{X