50mL of .1M HCl, how many moles H3O+?

50mL of 0.1M HCl, how many moles H₃O⁺?

HCl is a strong acid which completely dissociates in aqueous solution to give H₃O⁺ ions.
Molarity of H₃O⁺ ions = Molarity of HCl = 0.1 M = 0.1 mol/L
Volume of the solution = 50 mL = 0.050 L

No. of moles of H₃O⁺ ions = Molarity × Volume = (0.1 mol/L) × (0.050 L) = 0.005 mol


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0.1M solution of NaOH, moles of OH⁻ in 20.0 mL of this solution?

NaOH completely dissociates in aqueous solution to give OH⁻ ions.
Molarity of OH⁻ ions = Molarity of NaOH = 0.1 M = 0.1 mol/L
Volume of the solution = 20.0 mL = 0.0200 L

No. of moles of OH⁻ ions = Molarity × Volume = (0.1 mol/L) × (0.02000 L) = 0.002 mol