A 43.20 mL sample of 0.3260 M sodium hydroxide (NaOH) is required to react completely with 36.70 mL of a phosphoric acid (H3PO4) solution. What is the molarity of the phosphoric acid solution?
3NaOH + H3PO4 ==> 3H2O + Na3PO4
mols NaOH = M x L = ?
Using the coefficients in the balanced equation, convert mols NaOH to mols H3PO4.
Then M H3PO4 = mols H3PO4/L H3PO4 = ?
To determine the molarity of the phosphoric acid (H3PO4) solution, we can use the concept of stoichiometry.
First, we need to determine the number of moles of sodium hydroxide (NaOH) used in the reaction. We can use the formula:
moles of NaOH = volume of NaOH solution (in L) × molarity of NaOH solution
Converting the volume of the NaOH solution from milliliters to liters:
volume of NaOH solution = 43.20 mL ÷ 1000 mL/L = 0.04320 L
Substituting the known values into the formula:
moles of NaOH = 0.04320 L × 0.3260 M = 0.014105 moles
Since the balanced chemical equation for the reaction between NaOH and H3PO4 is:
3 NaOH + H3PO4 → Na3PO4 + 3 H2O
We can see that 3 moles of NaOH react with 1 mole of H3PO4. Therefore, the number of moles of H3PO4 in the reaction is also equal to 0.014105 moles.
To determine the molarity of the H3PO4 solution, we need to divide the moles of H3PO4 by the volume of the H3PO4 solution.
volume of H3PO4 solution = 36.70 mL ÷ 1000 mL/L = 0.03670 L
molarity of H3PO4 solution = moles of H3PO4 ÷ volume of H3PO4 solution
Substituting the known values:
molarity of H3PO4 solution = 0.014105 moles ÷ 0.03670 L ≈ 0.3843 M
Therefore, the molarity of the phosphoric acid (H3PO4) solution is approximately 0.3843 M.
To find the molarity of the phosphoric acid solution, we need to use the concept of stoichiometry and the balanced chemical equation for the reaction between sodium hydroxide (NaOH) and phosphoric acid (H3PO4).
The balanced chemical equation for the reaction is:
3NaOH + H3PO4 -> Na3PO4 + 3H2O
According to the balanced equation, one mole of phosphoric acid (H3PO4) reacts with three moles of sodium hydroxide (NaOH). Therefore, the moles of H3PO4 can be calculated using the following equation:
moles H3PO4 = (moles NaOH) x (3 moles H3PO4 ÷ 1 mole NaOH)
First, let's calculate the moles of NaOH:
moles NaOH = (volume NaOH solution in liters) x (molarity of NaOH)
Given:
Volume of NaOH solution = 43.20 mL = 43.20/1000 L = 0.04320 L (convert mL to L)
Molarity of NaOH = 0.3260 M
moles NaOH = 0.04320 L x 0.3260 M
Now, let's calculate the moles of H3PO4:
moles H3PO4 = moles NaOH x (3 moles H3PO4 ÷ 1 mole NaOH)
moles H3PO4 = (0.04320 L x 0.3260 M) x (3 mol H3PO4 ÷ 1 mol NaOH)
Finally, we can find the molarity of the phosphoric acid solution:
Molarity of H3PO4 = moles H3PO4 ÷ (volume of H3PO4 solution in liters)
Given:
Volume of H3PO4 solution = 36.70 mL = 36.70/1000 L = 0.03670 L (convert mL to L)
Molarity of H3PO4 = (moles H3PO4) ÷ (0.03670 L)
By plugging in the values obtained for the moles of H3PO4, we can calculate the molarity of the phosphoric acid solution.