What volume in mL of 0.0985 M sodium hydroxide solution is required to reach the equivalence point in the complete titration of a 15 mL sample of 0.124 M phosphoric acid?
15mL x(1L/1000mL)x(0.124mols/mol)x (3molNaOH/1molH3PO4)(1L/0.0985mol)x1000mL/1L= 56.6mL
dont cancel out the L to mL conversion just do this step by step, if its wrong correct me idk how it would be wrong tho i did exactly what the book did
H3PO4 + 3NaOH ==> 3H2O + Na3PO4
mols H3PO4 = M x L = ?
Using the coefficients in the balanced equation, convert mols H3PO4 to mols NaOH. That is mols H3PO4 x 3 = mols NaOH.
Now M NaOH = mols NaOH/L NaOH. YOu know M and mols, solve for L NaOH and convert to mL.
35.7 mL
To find the volume of sodium hydroxide (NaOH) solution required to reach the equivalence point in the titration, you need to use the concept of stoichiometry and the balanced chemical equation for the reaction between NaOH and phosphoric acid (H₃PO₄).
The balanced equation for the reaction is:
H₃PO₄ + 3NaOH → Na₃PO₄ + 3H₂O
From the balanced equation, we can see that the stoichiometric ratio between H₃PO₄ and NaOH is 1:3. This means that for every 1 mole of H₃PO₄, we need 3 moles of NaOH.
Given that the concentration of the H₃PO₄ solution is 0.124 M, we can determine the number of moles of H₃PO₄ present in the 15 mL sample using the equation:
moles of H₃PO₄ = (volume of H₃PO₄ solution in liters) × (concentration of H₃PO₄ in moles per liter)
Converting the volume to liters gives:
volume of H₃PO₄ solution = 15 mL × (1 L / 1000 mL) = 0.015 L
Now we can calculate the moles of H₃PO₄:
moles of H₃PO₄ = 0.015 L × 0.124 mol/L = 0.00186 mol
Since the stoichiometric ratio between H₃PO₄ and NaOH is 1:3, we need 3 times the number of moles of NaOH. Therefore:
moles of NaOH = 3 × moles of H₃PO₄ = 3 × 0.00186 mol = 0.00558 mol
Finally, to find the volume of the NaOH solution required, we can use the equation:
volume of NaOH solution = (moles of NaOH) / (concentration of NaOH in moles per liter)
Given that the concentration of the NaOH solution is 0.0985 M, we can calculate the volume of NaOH solution:
volume of NaOH solution = 0.00558 mol / 0.0985 mol/L = 0.0565 L
Converting the volume back to milliliters:
volume of NaOH solution = 0.0565 L × (1000 mL / 1 L) = 56.5 mL
Therefore, the volume of the 0.0985 M NaOH solution required to reach the equivalence point in the complete titration of the 15 mL 0.124 M H₃PO₄ solution is approximately 56.5 mL.