describe how you would prepare 500 mL 0.250 M ethylene glycol (MW=62.07) from concentrated 31% (w/w) solution that has a density of 1.0350 g/mL
31% w/w means 31.0 g ethylene glycol in 100 g solution.
mols ethylene glycol = grams/molar mass = about about 0.5 but you may need to do it more accurately.
Use density to convert 100 g soln to volume. volume = mass/density = 100/1.0350 = about 95 mL.
Then M = mols/L soln. Substitute and solve for M of the 31% material.
Then use the dilution formula of
c1v1 = c2v2 where\
c = concn
v = volume
and dilute the 31% material.
To prepare 500 mL of 0.250 M ethylene glycol, we will need to determine the amount of concentrated 31% ethylene glycol solution required. Here are the steps to follow:
Step 1: Calculate the molar mass of ethylene glycol (MW=62.07 g/mol).
Step 2: Determine the desired moles of ethylene glycol. The concentration is given as 0.250 M, and the volume is 500 mL. Therefore, moles = concentration x volume = 0.250 mol/L x 0.500 L = 0.125 mol.
Step 3: Convert the desired moles into grams using the molar mass. Mass = moles x molar mass = 0.125 mol x 62.07 g/mol = 7.75875 g.
Step 4: Calculate the volume of concentrated solution needed. Since the concentration is given in percent weight per weight (w/w), we need to convert it into grams per milliliter (g/mL). The density of the solution is given as 1.0350 g/mL.
Step 5: Determine the volume (V) of the concentrated solution required by dividing the mass by the density. V = mass / density = 7.75875 g / 1.0350 g/mL ≈ 7.503 mL.
To prepare 500 mL of a 0.250 M ethylene glycol solution, you will need approximately 7.503 mL of the concentrated 31% (w/w) ethylene glycol solution.
To prepare 500 mL of a 0.250 M ethylene glycol solution, you would first need to calculate the amount of ethylene glycol (in grams) required, based on its molar mass. Then, you can determine the volume of the concentrated solution needed to achieve the desired concentration. Here's a step-by-step breakdown:
1. Calculate the molar mass of ethylene glycol (MW = 62.07 g/mol).
2. Determine the number of moles of ethylene glycol required using the molarity formula:
Moles = Molarity × Volume (in liters)
Moles = 0.250 mol/L × 0.500 L
Moles = 0.125 mol
3. Calculate the mass of ethylene glycol required using the molar mass:
Mass = Moles × Molar mass
Mass = 0.125 mol × 62.07 g/mol
Mass = 7.75875 g (rounded to four decimal places)
4. Next, we need to find the volume of the concentrated solution that contains the 7.75875 g of ethylene glycol.
a. First, calculate the mass of the concentrated solution needed using the density:
Mass = Volume × Density
Mass = Volume × 1.0350 g/mL
b. Rearrange the equation to solve for volume:
Volume = Mass / Density
Volume = 7.75875 g / 1.0350 g/mL
Volume = 7.5 mL (rounded to one decimal place)
Therefore, to prepare 500 mL of a 0.250 M ethylene glycol solution, you would measure 7.5 mL of the concentrated 31% (w/w) solution and then dilute it with distilled water to reach a final volume of 500 mL.