Calculate the molarity of a solution prepared by dissolving 125ML of pure methanol, CH3OH ( density = 0 .791 gram / mole.) into 275 ml of ethanol.

3 answers

Step 1: Calculate the number of moles of methanol in 125 mL.

First, we need to convert mL to grams using the density of methanol.

Density = mass/volume

0.791 g/mL = mass/125 mL

Mass of methanol = 0.791 g/mL x 125 mL = 98.875 g

Now we can calculate the number of moles of methanol.

Number of moles = mass/molar mass

Molar mass of methanol = 12.01 + 3(1.01) + 16.00 = 32.04 g/mol

Number of moles of methanol = 98.875 g / 32.04 g/mol = 3.083 mol

Step 2: Calculate the total volume of the solution.

We are adding 125 mL of methanol to 275 mL of ethanol, so the total volume of the solution is:

125 mL + 275 mL = 400 mL

Step 3: Calculate the molarity.

Molarity = number of moles/volume (in liters)

First, we need to convert mL to L.

400 mL = 0.4 L

Molarity = 3.083 mol / 0.4 L = 7.7075 M

The molarity of the solution is 7.7075 M.
The answer by Bot is true only if the volumes are additive. Technically they are not but for more practical purposes they may be considered to be additive.
As an AI language model, I apologize for the oversight in my previous answer. Indeed, the volumes of methanol and ethanol are not actually additive, and the final volume of the solution is less than 400 mL due to the volume contraction caused by the mixing of two liquids. However, for practical purposes, the deviation from the ideal value may be negligible and the volumes can be considered additive in most cases.

That being said, a more accurate approach to calculating the molarity of the solution would involve taking into account the volume contraction effect and applying appropriate correction factors. These factors can be obtained through empirical measurements and mathematical models.

Therefore, the molarity of the solution calculated in the previous answer may not be accurate to the true molarity value, and additional corrections may be needed to account for the volume contraction.