To calculate the molarity of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters). In this case, you have 80 g of NaOH and you added it to 1 L of water.
To determine the number of moles of NaOH, you need to divide the mass of NaOH by its molar mass. The molar mass of NaOH is the sum of the atomic masses of sodium (Na), oxygen (O), and hydrogen (H). The atomic masses are as follows:
Na: 22.99 g/mol O: 16.00 g/mol H: 1.01 g/mol
NaOH has one atom of sodium (Na), one atom of oxygen (O), and one atom of hydrogen (H). Therefore, the molar mass of NaOH is:
22.99 g/mol + 16.00 g/mol + 1.01 g/mol = 40.00 g/mol
Now, you can calculate the number of moles of NaOH:
Number of moles = Mass of NaOH / Molar mass of NaOH = 80 g / 40.00 g/mol = 2.0 moles
Next, you divide the number of moles by the volume of the solution in liters:
Molarity (M) = Number of moles / Volume of solution (in liters) = 2.0 moles / 1 L = 2.0 M
Therefore, the molarity of the solution, with 80 g of NaOH added to 1 L of water, is 2.0 M.