You titrate a 10.0 mL sample of phosphoric acid with a 1.65 M solution of the base potassium hydroxide. It takes 7.55 mL to reach the endpoint of the titration. What is the molar concentration of the original solution of phosphoric acid?
3KOH + H3PO4 --> K3PO4 + 3H2O
H3PO4 + 3KOH ==> K3PO4 + 3H2O
mols KOH = M x L = ?
Convert mols KOH to mols H3PO4.
M H3PO4 = mols H3PO4/L H3PO4
To find the molar concentration of the original solution of phosphoric acid, you can use the concept of stoichiometry and the balanced equation for the reaction.
First, let's calculate the number of moles of potassium hydroxide (KOH) that reacts with the phosphoric acid (H3PO4) using the titration volume:
moles KOH = concentration of KOH * volume of KOH used
moles KOH = 1.65 M * 7.55 mL
Next, we need to determine the stoichiometric ratio between KOH and H3PO4 from the balanced equation:
3 moles KOH react with 1 mole H3PO4
Therefore, the moles of phosphoric acid can be calculated as:
moles H3PO4 = (moles KOH) / 3
Finally, to find the molar concentration of the original phosphoric acid solution, divide the moles of H3PO4 by the initial volume of the sample:
concentration of H3PO4 = (moles H3PO4) / (initial volume of sample)
Remember, the initial volume of the sample is given to be 10.0 mL.
Now, substitute the values:
moles H3PO4 = (1.65 M * 7.55 mL) / 3
concentration of H3PO4 = (moles H3PO4) / 10.0 mL
Calculate the values to find the molar concentration of the original phosphoric acid solution.