7.5 g of acetic acid (CH3COOH) are diluted to 150 mL with water. What is the molarity (mol/dm3) of the acetic acid?
mols acetic acid = grams/molar mass, then
M acetic acid = mols/L
To find the molarity of the acetic acid solution, we need to use the formula:
Molarity (M) = moles of solute / volume of solution in liters
First, let's find the moles of acetic acid in the solution:
moles of acetic acid = mass / molar mass
The molar mass of acetic acid (CH3COOH) is calculated by adding up the atomic masses:
C (12.01 g/mol) + H (1.01 g/mol) x 3 + C (12.01 g/mol) + O (16.00 g/mol) + O (16.00 g/mol) + H (1.01 g/mol) = 60.05 g/mol
moles of acetic acid = 7.5 g / 60.05 g/mol = 0.1249 mol
Next, we need to convert the volume of the solution to liters:
volume of solution = 150 mL = 150/1000 L = 0.150 L
Now, we can calculate the molarity:
Molarity (M) = 0.1249 mol / 0.150 L ≈ 0.833 M
Therefore, the molarity of the acetic acid solution is approximately 0.833 mol/dm^3.
To find the molarity (mol/dm³) of a solution, you need to determine the number of moles of solute (acetic acid) and then divide it by the volume of the solution in dm³.
Here's how you can solve this problem step by step:
Step 1: Convert the mass of acetic acid to moles.
The molar mass of acetic acid (CH3COOH) is:
C: 12.01 g/mol
H: 1.01 g/mol (3 hydrogen atoms)
O: 16.00 g/mol (2 oxygen atoms)
Molar mass of CH3COOH = (12.01 x 2) + (1.01 x 3) + 16.00 + 1.008 = 60.052 g/mol
To find the number of moles, divide the given mass by the molar mass:
Number of moles = mass / molar mass
Number of moles = 7.5 g / 60.052 g/mol
Step 2: Calculate the volume of the solution in dm³.
By diluting 7.5 g of acetic acid to 150 mL with water, the volume of the resulting solution is 150 mL or 0.15 dm³.
Step 3: Calculate the molarity.
Molarity (mol/dm³) = number of moles / volume of solution (in dm³)
Molarity = (7.5 g / 60.052 g/mol) / 0.15 dm³
Now you can do the calculations to find the molarity of the acetic acid solution.