Question

A 25.00-mL sample of an HNO, solution is titrated with 0.102 M NaOH. The titration requires 28.52 mL to reach the equivalence point. What is the concentration of the HNO, solution?

Select one or more:
a. 8.89 M
b. 0.102 M
c.0.0894 M
d. 0.116 M

Answer 1

The concentration of the HNO3 solution is calculated using the molarity of the NaOH solution and the volume of NaOH used at the equivalence point. With a 1:1 mole ratio in the reaction, the concentration of HNO3 is found to be 0.116 M.

Step-by-step explanation:

To determine the concentration of the HNO3 solution used in the titration with NaOH, we will use the concept of molarity and the balanced chemical equation for the reaction, which is:

HNO3 + NaOH → NaNO3 + H2O

Since the reaction has a 1:1 mole ratio between HNO3 and NaOH, we can find the number of moles of NaOH that reacted and, by extension, the number of moles of HNO3 that were present in the 25.00 mL sample. Using the molarity formula (Molarity = Moles of solute / Volume of solution in liters) and rearranging it, we can solve for the HNO3 concentration.

Moles of NaOH = Molarity of NaOH × Volume of NaOH in liters

Moles of NaOH = 0.102 M × 0.02852 L = 0.0029104 moles

Concentration of HNO3 = Moles of HNO3 (same as moles of NaOH) / Volume of HNO3 in liters

Concentration of HNO3 = 0.0029104 moles / 0.02500 L = 0.1164 M

The closest answer from the given options, rounded to three significant figures, is 0.116 M (option d).