how many grams of sodium chloride do you need to prepare 250 mL of a 5.00% sodium chloride solution?

5% means 5g NaCl in 100 g solution.

100 g has what volume?
mass = volume x density. If you know density you can calculate volume.
Then 5 g NaCl x (250 mL/volume) = xx g NaCl

To calculate the number of grams of sodium chloride needed to prepare a 5.00% solution, you need to know the density of the sodium chloride solution. Once you have the density, you can use the formula:

Mass = Volume × Density

However, since the density of the sodium chloride solution is not given, we can assume that the density of a sodium chloride solution is close to the density of water, which is approximately 1 g/mL.

Using the formula, we can calculate the mass of sodium chloride needed.

Volume of solution = 250 mL
Concentration of sodium chloride = 5.00%

First, convert the volume from mL to L:
250 mL ÷ 1000 mL/L = 0.25 L

To determine the mass of sodium chloride, we multiply the volume by the density:
0.25 L × 1 g/mL = 0.25 g of sodium chloride

Therefore, you would need approximately 0.25 grams of sodium chloride to prepare 250 mL of a 5.00% sodium chloride solution, assuming the density of the sodium chloride solution is similar to water.