An acid-base titration is performed to find the concentration of sodium hydroxide. 50.0 mL of a solution of sodium hydroxide is neutralized by exactly 24.50 mL of hydrochloric acid of concentration 0.250 mol/L.
NaOH + HCl → NaCl + H2O
Calculate the concentration, in mol/L, of the sodium hydroxide solution.
Reaction: NaOH + HCl → NaCl + H2O
Moles = concentration (mol/L) x volume of solution (mL) = 0.25 x 24.5/1000 = 0.006125 mol
Use the stoichiometry of the balanced equation to calculate the moles of NaOH. The balanced equation shows that 1 mol of NaOH reacts with every 1 mol of HCl.
Moles of NaOH = moles of HCL = 0.006125 mol
Concentration (mol/L) = number of moles of solute (mol)/ volume of solution = 0.006125 /(50/1000) = 0.123 mol/L
Final concentration (mol/L) = concentration (mol/L) x dilution factor = 0.123 x 10 = 1.23 mol/L
*The answer is given in three significant figures because it’s the smallest number of significant figures provided in the data.