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Calculate the volume of NaOH (in mL) needed to reach the equivalence point.

Given:
[tex]\[ 0.00245 \, \text{mol} \, \text{HNO}_3 = 0.00245 \, \text{mol} \, \text{NaOH} \][/tex]

Calculate:
[tex]\[ (0.098 \, \text{M})(25 \, \text{mL}) = 0.00245 \, \text{mol} \][/tex]

4. Calculate the anticipated pH at the equivalence point in problem 3.



Answer :

GinnyAnswer
To solve this problem, we need to calculate the volume of NaOH that will be needed to reach the equivalence point and the pH at that point. Let's detail this step-by-step:

Step 1: Determine the number of moles of HNO₃

We know that 0.098 moles of HNO₃ are in 25 mL of solution. To find the total moles of HNO₃:

[tex]\[ \text{n}_{\text{HNO}_3} = 0.098 \times 25 \][/tex]

[tex]\[ \text{n}_{\text{HNO}_3} \approx 3 \][/tex]

So, the number of moles of HNO₃ is approximately 3 moles (rounded value).

Step 2: Determine the number of moles of NaOH

The problem states that you have 0.00245 moles of NaOH.

Step 3: Calculate the volume of NaOH needed

To find the volume of NaOH needed to reach the equivalence point, we need to use the molarity formula:

[tex]\[ \text{Molarity} = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \][/tex]

We know the molarity (concentration) of the NaOH solution is 0.227 M. Rearranging the formula to solve for volume:

[tex]\[ \text{Volume (L)} = \frac{\text{moles of NaOH}}{\text{molarity of NaOH}} \][/tex]

[tex]\[ \text{Volume (L)} = \frac{0.00245}{0.227} \][/tex]

[tex]\[ \text{Volume (L)} \approx 0.010793 \text{ L} \][/tex]

To convert this to milliliters (mL):

[tex]\[ \text{Volume (mL)} = 0.010793 \times 1000 \][/tex]

[tex]\[ \text{Volume (mL)} \approx 10.793 \][/tex]

So, the volume of NaOH needed is approximately 10.793 mL.

Step 4: Determine the pH at the equivalence point

At the equivalence point in a titration between a strong acid (HNO₃) and a strong base (NaOH), the solution is neutral. This means that the pH at the equivalence point is:

[tex]\[ \text{pH}_{\text{equivalence point}} = 7 \][/tex]

Summary of the results:

1. The number of moles of HNO₃ is approximately 3.
2. The number of moles of NaOH is 0.00245.
3. The volume of NaOH needed is approximately 10.793 mL.
4. The anticipated pH at the equivalence point is 7.

This step-by-step solution helps you understand how to find the volume of NaOH needed for the titration and the pH at the equivalence point.

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