0.5123 g KHP sample was dissolved in about 25 mL of distilled water, and titrated to the phenolphthalein endpoint with 28.75 mL of a sodium hydroxide solution. Calculate the molar concentration of the hydroxide solution
KHP + NaOH ==> NaHP + H2O
moles KHP = grams/molar mass
Solve for moles.
Look at the equation; it is 1:1 so moles KHP = moles NaOH.]
The M NaOH = moles NaOH/L NaOH.
To calculate the molar concentration of the sodium hydroxide solution, we need to use the concept of stoichiometry.
The balanced chemical equation for the reaction between potassium hydrogen phthalate (KHP) and sodium hydroxide (NaOH) is:
KHP + NaOH -> KNaP + H2O
From the equation, we can see that the stoichiometric ratio between NaOH and KHP is 1:1. This means that for every 1 mole of NaOH reacting, 1 mole of KHP is consumed.
First, we need to calculate the number of moles of KHP that reacted.
We are given the mass of KHP as 0.5123 g. To convert this to moles, we need to divide by the molar mass of KHP. The molar mass of KHP is the sum of the atomic masses of all the atoms in the formula.
The chemical formula of KHP is C8H5KO4.
The atomic masses are:
- Carbon (C): 12.01 g/mol
- Hydrogen (H): 1.008 g/mol
- Potassium (K): 39.10 g/mol
- Oxygen (O): 16.00 g/mol
So, the molar mass of KHP is:
(8 * 12.01 g/mol) + (5 * 1.008 g/mol) + 39.10 g/mol + (4 * 16.00 g/mol) = 204.23 g/mol
To calculate the moles of KHP, we divide the given mass by the molar mass:
0.5123 g / 204.23 g/mol = 0.00251 mol
Now, since the stoichiometric ratio between NaOH and KHP is 1:1, the moles of NaOH that reacted will also be 0.00251 mol.
The volume of the sodium hydroxide solution used is given as 28.75 mL.
To convert this volume to liters, we divide by 1000:
28.75 mL / 1000 = 0.02875 L
Finally, to calculate the molar concentration of the sodium hydroxide solution, we use the formula:
Molarity (M) = moles of solute / volume of solution in liters
Molarity = 0.00251 mol / 0.02875 L = 0.0874 M
Therefore, the molar concentration of the sodium hydroxide solution is 0.0874 M.
To calculate the molar concentration of the sodium hydroxide (NaOH) solution, first we need to find the number of moles of potassium hydrogen phthalate (KHP) that reacted with the NaOH solution. The balanced chemical equation for the reaction between KHP and NaOH is:
KHP + NaOH -> KNaP + H2O
From the equation, we can see that 1 mole of KHP reacts with 1 mole of NaOH. Thus, the number of moles of KHP is equal to the number of moles of NaOH.
Given that the mass of the KHP sample is 0.5123 g, we need to calculate the number of moles of KHP using its molar mass. The molar mass of KHP is:
Molar mass of KHP = 204.23 g/mol
Number of moles of KHP = Mass of KHP / Molar mass of KHP
= 0.5123 g / 204.23 g/mol
= 0.002511 mol
Since the number of moles of KHP is equal to the number of moles of NaOH, the molar concentration of the NaOH solution can be calculated using the volume and number of moles of NaOH used in the titration.
Volume of NaOH solution used = 28.75 mL
= 0.02875 L
Molar concentration of NaOH solution = Number of moles of NaOH / Volume of NaOH solution used
= 0.002511 mol / 0.02875 L
≈ 0.0873 mol/L
Therefore, the molar concentration of the NaOH solution is approximately 0.0873 mol/L.