If 0.176 g of pure sodium hydroxide was dissolved in water and the solution titrated with 5.05 mL of hydrochloric acid solution to a phenolphthalein end point, calculate each of the following of the hydrochloric acid solution.
(a) the molarity = .871
(b) the percent by mass (density of solution = 1.016 g/mL)
mols NaOH = grams/molar mass = ?
a. 0.871 is correct for M.
b.
1.016 g/mL x 1000 mL x (?%/100) x (1/36.5) = 0.871
Solve for ?
To calculate the values of the hydrochloric acid solution, we need to use the given information and perform some calculations. Let's break down the steps.
(a) Calculating the Molarity of the Hydrochloric Acid Solution:
To determine the molarity (M) of the hydrochloric acid solution, we need to use the concept of stoichiometry and the volume and concentration of the sodium hydroxide solution.
1. Convert the mass of sodium hydroxide (NaOH) to moles:
Mass of NaOH = 0.176 g
Molar mass of NaOH = 23.0 g/mol (sodium) + 16.0 g/mol (oxygen) + 1.0 g/mol (hydrogen)
= 40.0 g/mol
Moles of NaOH = Mass of NaOH / Molar mass of NaOH
2. Calculate the moles of hydrochloric acid (HCl) used:
According to the balanced chemical equation, the stoichiometry between NaOH and HCl is 1:1. Hence, the moles of NaOH are equal to the moles of HCl used in the titration.
Moles of HCl = Moles of NaOH
3. Calculate the volume of the hydrochloric acid solution:
The volume of the hydrochloric acid solution used in the titration is given as 5.05 mL.
4. Finally, calculate the molarity of the hydrochloric acid solution:
Molarity (M) = Moles of HCl / Volume of HCl solution (in liters)
= Moles of HCl / (5.05 mL / 1000 mL per L)
= Moles of HCl / 0.00505 L
Therefore, to get the molarity (M) of the hydrochloric acid solution, divide the moles of HCl by 0.00505 L.
(b) Calculating the Percent by Mass of the Hydrochloric Acid Solution:
To determine the percent by mass of the hydrochloric acid solution, we need to use the density of the solution and the molarity calculated in part (a).
1. Calculate the mass of the hydrochloric acid used in the titration:
Mass of HCl = Molarity (M) × Volume of HCl solution (in liters) × Molar mass of HCl
2. Calculate the percent by mass of the hydrochloric acid solution:
Percent by mass = (Mass of HCl / Mass of solution) × 100%
= (Mass of HCl / (Volume of HCl solution × Density of solution)) × 100%
Therefore, to get the percent by mass of the hydrochloric acid solution, divide the mass of HCl by (volume of HCl solution × density of the solution) and multiply by 100%.