What is the molarity of a solution prepared from 15.0 grams of methanol (ch3oh, density = 0.792 g/ml) with 185.0 milliliters of
1 answer:
Taking into account the definition of molarity, the molarity of the solution is 2.2958 .
Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.
The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:
molarity= number of moles÷ volume of solution
Molarity is expressed in units .
In this case, you have a a solution prepared from:
- 15.0 grams of methanol (CH₃OH, density = 0.792 g/ml).
- 185.0 milliliters of ethanol (CH₃CH₂OH)
Being the molar mass of methanol 32.04 g/mol, that is the amount of mass that the compound contains in one mole, the number of moles of methanol in the solution is calculated as:
Moles of methanol (solute) = mass ÷molar mass = 15.0 grams/ 32.04 g/mol
<u><em>Moles of methanol (solute) = 0.4682 moles</em></u>
On the other side, being the density of methanol 0.792 g/mL, this is the amount of mass in a certain volume of the compound, the volume of methanol can be calculated as:
Volume of methanol = mass ÷density = 15.0 g/ 0.792 g/mL
<u><em>Volume of methanol= 18.939 mL</em></u>
Being the volume of ethanol 185 mL, the volume of solution can be calculated as:
Volume of solution = Volume of methanol (solute) + Volume of ethanol (solvent)
Volume of solution = 18.939 mL + 185 ml = 203.939 mL= 0.203939 L (being 1000 mL= 1 L)
Replacing in the definition of molarity:
molarity= 0.4682 moles÷ 0.203939 L
Solving:
<u><em>molarity= 2.2958 </em></u>
Finally, the molarity of the solution is 2.2958 .
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