To determine the molarity of NaOH solution, student took 3.5 g of KHP (KHP – Potassium hydrogen phthalate; Molar mass = 204.22 g/mol) and dissolved in 50 mL of water and titrated with the given unknown molarity NaOH solution loaded in burette. His burette volume read 1.85 mL at the start of the experiment and 24.65 mL when the phenolphthalein indicator turned pink.
NaOH + KHP ==> NaKP + H2O
mols KHP = grams/molar mass = ?
mols KHP = mols NaOH (the ratio is 1 mol KHP to 1 mol NaOH in the equation).
M NaOH = mols NaOH/L NaOH = ?
Note: volume NaOH = 24.65 mL - 1.85 mL = ? mL. Convert to L.
To determine the molarity of the NaOH solution, we can use the concept of stoichiometry and the titration equation. Here are the steps to calculate the molarity of the NaOH solution:
Step 1: Calculate the moles of KHP (Potassium hydrogen phthalate) used.
- Use the formula: Moles = Mass / Molar mass
- Given: Mass of KHP = 3.5 g and Molar mass of KHP = 204.22 g/mol
- Substituting the values, we have: Moles of KHP = 3.5 g / 204.22 g/mol
Step 2: Calculate the moles of NaOH that reacted with the KHP.
- Consider the balanced equation between KHP and NaOH:
KHP + NaOH -> Water + Salt
- From a stoichiometric point of view, the ratio between KHP and NaOH is 1:1.
- Therefore, the moles of NaOH that reacted with KHP are equal to the moles of KHP: Moles of NaOH = Moles of KHP
Step 3: Calculate the volume of NaOH solution used.
- Fill in the given burette volume readings:
Initial burette volume = 1.85 mL
Final burette volume = 24.65 mL
- Calculate the volume of NaOH solution used in the titration:
Volume of NaOH used = Final burette volume - Initial burette volume
Volume of NaOH used = 24.65 mL - 1.85 mL
Step 4: Convert the volume of NaOH solution used to liters.
- Since the units of molarity are in mol/L, convert the volume of NaOH solution used in milliliters to liters:
Volume of NaOH used = (24.65 mL - 1.85 mL) / 1000 mL/L
Step 5: Calculate the molarity of the NaOH solution.
- Use the formula: Molarity = Moles / Volume
- Substitute the values in the formula: Molarity of NaOH = Moles of NaOH / Volume of NaOH used
By following these steps, you can determine the molarity of the NaOH solution. Make sure to substitute the calculated values accurately to get the final result.
To determine the molarity of the NaOH solution, we can use the concept of stoichiometry and the balanced chemical equation for the reaction between NaOH and KHP.
The balanced equation for the reaction is:
NaOH + KHP -> NaKP + H2O
From the balanced equation, we can see that the ratio between NaOH and KHP is 1:1. This means that 1 mole of NaOH reacts with 1 mole of KHP.
First, we need to calculate the number of moles of KHP used in the experiment. We can use the formula:
moles = mass / molar mass
Given that the mass of KHP used is 3.5 g and the molar mass of KHP is 204.22 g/mol, we can calculate the moles of KHP as follows:
moles of KHP = 3.5 g / 204.22 g/mol
Next, we need to calculate the number of moles of NaOH used in the reaction. Since the stoichiometry of the balanced equation is 1:1, the number of moles of NaOH is equal to the number of moles of KHP.
moles of NaOH = moles of KHP
Now, we can calculate the molarity of the NaOH solution. The formula for molarity is:
molarity = moles of solute / volume of solution (in liters)
The volume of the solution used in the titration is given as 50 mL. We need to convert this to liters by dividing by 1000.
volume of solution = 50 mL / 1000 = 0.05 L
Using this information, we can calculate the molarity of the NaOH solution as follows:
molarity = moles of NaOH / volume of solution
Substituting the values:
molarity = moles of KHP / volume of solution
molarity = (3.5 g / 204.22 g/mol) / 0.05 L
Now, we can calculate the molarity:
molarity = 0.00857 mol / 0.05 L
molarity = 0.1714 M
Therefore, the molarity of the NaOH solution is 0.1714 M.