Question

A chemistry student wants to prepare 250 mL of 0.15 M NaOH solution from a solid compound. What mass of NaOH is required to achieve this concentration?

Answer 1

To calculate the mass of NaOH required, we can use the formula:mass = volume  molarity  molar massFirst, we need to find the molar mass of NaOH. The atomic masses of the elements are as follows:- Sodium  Na : 22.99 g/mol- Oxygen  O : 16.00 g/mol- Hydrogen  H : 1.01 g/molSo, the molar mass of NaOH is:NaOH = 22.99 g/mol  Na  + 16.00 g/mol  O  + 1.01 g/mol  H  = 40.00 g/molNow, we can calculate the mass of NaOH required:mass =  250 mL    0.15 mol/L    40.00 g/mol First, we need to convert the volume from mL to L:250 mL = 250/1000 L = 0.250 LNow, we can plug in the values:mass =  0.250 L    0.15 mol/L    40.00 g/mol  = 1.50 gSo, the student needs 1.50 grams of solid NaOH to prepare 250 mL of 0.15 M NaOH solution.