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Title: How can I calculate the concentrations of hydrogen and hydroxide ions in a solution of sodium hydroxide? Post by: smmoh4 on Feb 14, 2013 if 2.50 grams of NaOH is dissolved in water to give 2.00 L of the solution, then how can I calculate the concentrations of the hydrogen and hydroxide ions in it?
Title: How can I calculate the concentrations of hydrogen and hydroxide ions in a solution of sodium hydroxide? Post by: iliketorifk on Feb 14, 2013 Find the molar mass of NaOh and use stoichiometry to find moles. Then divide that total by the liters to get a molarity, which will also be your concentration value.
Title: How can I calculate the concentrations of hydrogen and hydroxide ions in a solution of sodium hydroxide? Post by: tosha.garza on Feb 14, 2013 Lancenigo di Villorba (TV), Italy
You played about NaOH (e.g. Sodium Hydroxide) in aqueous solutions NaOH(aq) ---> Na+(aq) + OH-(aq) for complete dissociation by ionic way. Once you used 2.5 g 2.5 / 40 = 6.25E-2 mol these molar amount is dissoluted to give a 2.0 Liter of solutions |Na+| = |OH-| = 6.25E-2 / 2.0 = 3.125E-2 M So, YOU HAVE TO REMEMBER THAT THIS SOLUTE AFFECT SELF-DISSOCIATION OF WATER 2 H2O(aq) ---> OH-(aq) + H3O+(aq) A CHEMICAL PHENOMENON OBEYING TO AN EQUILIBRIUM Kw = |H3O+| * |OH-| WHICH BECOMES AT T=25°C=88°F Kw = 1.0E-14 = |H3O+| * |OH-| SO YOU MAY GIVE |OH-| = 3.125E-2 M |H3O+| = 1.0E-14 / 3.125E-2 = 3.2E-13 M pH = -log(|H3O+|) = 12.5 I hope this helps you. Title: How can I calculate the concentrations of hydrogen and hydroxide ions in a solution of sodium hydroxide? Post by: rivs9 on Feb 14, 2013 First determine how many mols of NaOH you have.
n=m/M, m= 2.50 g and M, the molecular mass of NaOH, is 40 g/mol. You have therefore n= 0.0625 mol NaOH There are as many molecules(mol) NaOH as are molecules (mol) of OH-. That means you have 0.0625 mol OH- and because there are as many atoms(mol) H as there are molecules (mol) OH- you have 0.0625 mol H. Remember 1 mol consists of 6.023*10^23 atoms or molecules |