how many mls of glycerol (FW= 92.1; density=1.26g/ml) must be used to make 250ml of a 0.15 M solution

M = moles/L

You know M and L, solve for moles.

Then moles = grams/molar mass
You know moles and molar mass, solve for grams.

Using density, convert grams to mL.

To determine the number of milliliters (ml) of glycerol needed to make a 0.15 M solution with a volume of 250 ml, you'll need to calculate the amount of glycerol in moles.

First, we'll determine the number of moles of glycerol needed by using the formula:

moles = concentration (M) × volume (L)

Convert the volume from milliliters (ml) to liters (L):

250 ml = 250/1000 L
= 0.25 L

Now use the formula to calculate the number of moles of glycerol:

moles = 0.15 M × 0.25 L
= 0.0375 moles

Since we know the molar mass (FW) of glycerol is 92.1 g/mol, we can convert moles to grams:

grams = moles × molar mass
= 0.0375 moles × 92.1 g/mol
≈ 3.463 g

Now, we can calculate the volume of glycerol by dividing this mass by its density:

volume = mass / density
= 3.463 g / 1.26 g/ml
≈ 2.75 ml

Therefore, approximately 2.75 ml of glycerol is needed to make 250 ml of a 0.15 M solution.