In an experiment, Tom dissolved 2.125 g of NaOH to make 200.0 mL of aqeous solution. What is the NaOH molarity?
Dr. O'Neal
To find the molarity (M) of a solution, you need to know the number of moles of solute (NaOH) and the volume of the solution.
First, let's find the number of moles of NaOH:
Step 1: Calculate the molecular weight of NaOH:
Atomic weight of Na (sodium) = 22.99 g/mol
Atomic weight of O (oxygen) = 16.00 g/mol
Atomic weight of H (hydrogen) = 1.01 g/mol
Molecular weight of NaOH = (1 x 22.99 g/mol) + (1 x 16.00 g/mol) + (1 x 1.01 g/mol) = 39.99 g/mol
Step 2: Calculate the number of moles of NaOH by dividing the mass by the molecular weight:
Number of moles of NaOH = 2.125 g / 39.99 g/mol = 0.0531 mol
Now, let's determine the volume of the solution:
The volume of the solution is given as 200.0 mL, but it is more convenient to use liters for the molarity calculation. Convert 200.0 mL to liters by dividing by 1000:
Volume of solution = 200.0 mL / 1000 mL/L = 0.200 L
Finally, we can calculate the molarity (M) of the NaOH solution using the formula:
Molarity (M) = moles of solute (NaOH) / volume of solution (in liters) = 0.0531 mol / 0.200 L = 0.2655 M
Therefore, the NaOH molarity is 0.2655 M.