A 5.00 mL sample of an aqueous solution of H3PO4 requires 43.2mL of 0.285M NaOH to convert all of the H3PO4 to Na2HPO4. The other product of the reaction is water.
Calculate the molarity of the H3PO4 solution.
H3PO4 + NaOH ==> NaH2PO4 + H2O
mols NaOH = M x L = ?
1 mol NaOH = 1 mol H3PO4
M H3PO4 = mols H3PO4/L H3PO4.
To calculate the molarity of the H3PO4 solution, we can use the equation:
H3PO4 + 3NaOH → Na3PO4 + 3H2O
We know that a 5.00 mL sample of the H3PO4 solution requires 43.2 mL of 0.285 M NaOH to react completely.
Let's start by calculating the number of moles of NaOH used in the reaction using the given volume and molarity:
moles of NaOH = volume of NaOH solution (L) x molarity of NaOH (mol/L)
= 0.0432 L x 0.285 mol/L
= 0.012312 mol
According to the balanced equation, 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.
As a result, the number of moles of H3PO4 in the 5.00 ml sample is:
moles of H3PO4 = (1/3) x moles of NaOH
= (1/3) x 0.012312 mol
= 0.004104 mol
Now, we can calculate the molarity of the H3PO4 solution using the volume of the sample and the number of moles of H3PO4:
molarity of H3PO4 = moles of H3PO4 / volume of H3PO4 solution (L)
= 0.004104 mol / (5.00 mL x 1 L/1000 mL)
= 0.8208 mol/L
Therefore, the molarity of the H3PO4 solution is 0.8208 M.
To calculate the molarity of the H3PO4 solution, you need to use the concept of stoichiometry and the volume and concentration of NaOH used in the reaction. Here's how you can do it step by step:
Step 1: Write the balanced chemical equation for the reaction:
H3PO4 + 2NaOH → Na2HPO4 + 2H2O
Step 2: Use the stoichiometric coefficients from the balanced equation to establish the mole ratio between H3PO4 and NaOH. In this case, the mole ratio is 1:2. This means that for every 1 mole of H3PO4, 2 moles of NaOH are required for the reaction.
Step 3: Calculate the number of moles of NaOH used in the reaction. Since the volume and concentration of NaOH are given, you can use the formula:
moles = volume (L) × concentration (M)
moles of NaOH = 43.2 mL × (1 L/1000 mL) × 0.285 M
Step 4: Calculate the number of moles of H3PO4 used in the reaction. Since the mole ratio between H3PO4 and NaOH is 1:2, the number of moles of H3PO4 is half the number of moles of NaOH:
moles of H3PO4 = (1/2) × moles of NaOH
Step 5: Calculate the molarity of the H3PO4 solution. The molarity (M) of a solution is defined as the number of moles of solute divided by the volume of the solution in liters:
Molarity of H3PO4 = moles of H3PO4 / volume of H3PO4 (L)
Given that the volume of the H3PO4 solution is 5.00 mL (which is equivalent to 0.005 L), you can now calculate the molarity:
Molarity of H3PO4 = moles of H3PO4 / 0.005 L
By plugging in the values obtained from the previous calculations, you can find the molarity of the H3PO4 solution.