A solution of ethanol (C2H5OH) in water is prepared by dissolving 76.9 mL of ethanol (density 0.79 g/cm^3) in enough water to make .250 L of solution. What is the molarity of ethanol in this solution?
2.24M
0.79g/ml x 76.9ml = 60.7g
60.7g /46.06 = 1.3 mole
1.3/ 0.25 L = 5.2M
To find the molarity of ethanol in the solution, we need to first calculate the moles of ethanol and then divide it by the volume of the solution in liters.
Step 1: Find the mass of ethanol.
We can calculate the mass of ethanol by multiplying the volume of ethanol by its density.
Mass = Volume × Density
Mass = 76.9 mL × 0.79 g/cm^3
Step 2: Convert mass from grams to moles.
To convert the mass of ethanol to moles, we need the molar mass of ethanol. The molar mass of ethanol (C2H5OH) can be calculated by adding up the atomic masses of carbon (C), hydrogen (H), and oxygen (O).
Molar mass of ethanol = (2 × atomic mass of carbon) + (6 × atomic mass of hydrogen) + atomic mass of oxygen
Step 3: Calculate the moles of ethanol.
Moles = Mass / Molar mass
Step 4: Calculate the molarity of ethanol.
Molarity = Moles / Volume
Let's calculate each step one by one.
Step 1:
Mass = 76.9 mL × 0.79 g/cm^3
= 60.751 g
Step 2:
Molar mass of ethanol = (2 × 12.01 g/mol) + (6 × 1.01 g/mol) + 16.00 g/mol
= 46.07 g/mol
Step 3:
Moles = Mass / Molar mass
= 60.751 g / 46.07 g/mol
Step 4:
Molarity = Moles / Volume
= (60.751 g / 46.07 g/mol) / 0.250 L
Now, let's calculate the molarity.
Molarity = (60.751 g / 46.07 g/mol) / 0.250 L
After performing the calculation, the molarity of ethanol in the solution is obtained.
Calculate the mass of ethanol (m) used from the volume and the density.
Calculate the RMM for ethanol
Then use m/RMM to calculate the number of moles (M) of ethanol.
I presume the final volume is 0.250 L rather than 250 L.
The molarity is then M/0.250 L