Need help understanding how to get number 6 & 7 , explanations would be great ut

Question

Need help understanding how to get number 6 & 7 , explanations would be great ution 1n. (11.1 8 19 202 4 2. Prepare a graph of the volume of NaOH added to vs. the pH of the solution. Ensure that all axis are properly labeled. Attach the graph to the data sheet From the graph, determine the volume of Na0H required to reach the equivalence point of the titration. Annotate this value on the graph and record the value below. 3. Vol NaOH at eg, pt.-0-nie - 4. Calculate the volume of NaOH required to reach the half equivalence point. Annotate this value on the graph and record the value below. vol Naoh at halfe pt. 1.95ml vel NaoiH at hafte t15mL From the graph, what is the pH at the half equivalence point? Annotate this value on the graph and record the value below. 5. pHat half eq. pt. 0-1 pm - 6. Using the values above, what is the K, of your unknown acid? 7. Based on the K, that you calculated, what is the identity of the unknown acid you analyzed? Unknown acid identity:

Explanation / Answer

At half equivalence point,

1/2 the volume required to neutralize the acid has been added.

Approximately 1/2[HA]initial has reacted to form A.

Therefore,[HA] [A]

Now, pH = pKa + log [A]/ [HA]; at [HA] [A], log[1] = 0

and hence, pH pKa.

Now, pKa = 5.04.

6. Therefore, Ka = 10-5.04

7.  The weak acids considered typically have Ka values that range from about 10–2 to about 10–10, or pKa values between 2 and 10. Also, larger the value of pKa, the weaker the acid.

Hence, the above acid is WEAK.

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---