how do i calculate a weight/vol % from a molarity given the density?

Molarity is 0.0303 M density = 1.52 g/mL, molar mass is 41.99 g/mol.

also we had 0.3885 grams dissolved into a 100 mL vol flask... hmmm

The second one is easier than the first.

wt/vol% = (grams solute/100 ml solution) = 0.3885 g/100 mL = 0.3885 % w/v

For #1, you have a molarity of 0.0303. That means you have 0.0303 mols/L solution.
0.0303 x 41.99 = about 1.3 g/L
Approx (1.3/1000)&100 = ?% w/v

thank you :)

To calculate the weight/volume percent (% w/v) from molarity and density, you'll need to follow these steps:

Step 1: Convert Molarity to moles per milliliter (mol/mL).

To convert molarity (M) to moles per milliliter (mol/mL), you need to multiply it by the molar volume. The molar volume is the volume occupied by one mole of a substance and is typically expressed in liters/mol. Since density is given in g/mL, we need to convert to liters/mol by dividing by 1000. So:

Molarity (mol/mL) = Molarity (M) / 1000

In this case, Molarity = 0.0303 M, so:

Molarity (mol/mL) = 0.0303 M / 1000 = 0.0000303 mol/mL

Step 2: Convert moles per milliliter to grams per milliliter (g/mL).

To convert moles per milliliter (mol/mL) to grams per milliliter (g/mL), you need to multiply it by the molar mass (g/mol). The molar mass is the mass of one mole of the substance. In this case, the molar mass is given as 41.99 g/mol. So:

Grams per milliliter (g/mL) = Molarity (mol/mL) * Molar mass (g/mol)

Grams per milliliter (g/mL) = 0.0000303 mol/mL * 41.99 g/mol = 0.001272 g/mL

Step 3: Calculate the weight/volume percent (% w/v).

The weight/volume percent (% w/v) is calculated by dividing the mass (in grams) of solute (substance being dissolved) by the volume (in milliliters) of the solution and multiplying by 100. The mass of solute is calculated by multiplying the grams per milliliter (g/mL) obtained in Step 2 by the density (g/mL) of the solution.

Weight/volume percent (% w/v) = (Grams per milliliter (g/mL) * Density (g/mL)) * 100

Weight/volume percent (% w/v) = (0.001272 g/mL * 1.52 g/mL) * 100 = 0.1934 %

Therefore, the weight/volume percent (% w/v) of the solution is approximately 0.1934 %.