Q12. (Points: 4) - Discuss your value of the methyl red pKa and compare it with a published...

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Q12. (Points: 4)  - Discuss your value of the methyl red pKa and compare it with a published literature value  what is the pKa, what does it represent and so what does this value tell you about methyl red? Methyl red is a common acid base indicator, does the pKa of methyl red influence how methyl red behaves as an indicator?  These are all aspects to consider in your discussion  13. Conclusion  (Points: 2)   Write a short conclusion outlining your main findings from the experiment XXXXXXXXXXReference MR  (Points: 1)  Using the Harvard format quote the reference you have used to obtain the literature value for methyl red in your discussion  12. MR Discussion MCQ  (Points: 3)   Which of the following have been discussed in your report?  Choose up to 5 options XXXXXXXXXXa. A comparison of your value of pKa with a literature value of methyl red     b. The molar extinction coefficient of methyl red suggests it absorbes little light     c. The pKa of methyl red suggests methyl red is a weak acid     d. The molar extinction coefficient of methyl red suggests it strongly absorbes light     e. pKa is a measure of acid concentration     f. The pKa of methyl red represents the pH at which methyl red is completely in the yellow base form     g. The pKa of methyl red represents the pH at which methyl red is completely in the red acid form     h. Methyl red acts as an acid base indicator but this is independent of the pKa     i. The pKa of methyl red will determine the colour change of methyl red as an acid base indicator     j. The pKa of methyl red suggests methyl red is a strong acid     k. A comparison of your value of molar extinction coefficient with a literature value of methyl red  
	
Document Preview: Q12. (Points: 4)  - Discuss your value of the methyl red pKa and compare it with a published literature value what is the pKa, what does it represent and so what does this value tell you about methyl red? Methyl red is a common acid base indicator, does the pKa of methyl red influence how methyl red behaves as an indicator?  These are all aspects to consider in your discussion13. Conclusion (Points: 2)   Write a short conclusion outlining your main findings from the experiment14. Reference MR (Points: 1)  Using the Harvard format quote the reference you have used to obtain the literature value for methyl red in your discussion12. MR Discussion MCQ (Points: 3)   Which of the following have been discussed in your report?Choose up to 5 options. a. A comparison of your value of pKa with a literature value of methyl red  b. The molar extinction coefficient of methyl red suggests it absorbes little light c. The pKa of methyl red suggests methyl red is a weak acid d. The molar extinction coefficient of methyl red suggests it strongly absorbes light e. pKa is a measure of acid concentration f. The pKa of methyl red represents the pH at which methyl red is completely in the yellow base form g. The pKa of methyl red represents the pH at which methyl red is completely in the red acid form h. Methyl red acts as an acid base indicator but this is independent of the pKa i. The pKa of methyl red will determine the colour change of methyl red as an acid base indicator j. The pKa of methyl red suggests methyl red is a strong acid k. A comparison of your value of molar extinction coefficient with a literature value of methyl red 

David · Accepted Answer

Q12. (Points: 4)  
- Discuss your value of the methyl red pKa and compare it with a published literature value 
Answer:  Ka is an acid dissociation constant. For convenience, the strength of an acid is generally indicated by its pKa value rather than Ka value 
pKa = -log10Ka
Smaller the pKa, the stronger the acid (the better it is as a proton donor). 
The pKa value of weak acid is in between 1 to 15 in water.  
The average pKa value calculated from the six determinations is 4.3.  This pKa value suggests that Methyl red is a weak acid.
 According to the literature the pka value of methyl red is 5.1, while the pka value of methyl red calculated from the experimental data is 4.3. The lower observed value of pKa then reported in the literature is may be due to the  higher extent of ionization of methyl red or may be due to excess of HCl. 
Methyl red is a commonly used indicator that has distinctly different colours in the ionised and unionised forms. According to literature it changes colour in the transition pH range (4.4 6.2), which is approximately pKa ± 1. This shows that a solution of methyl red will be red if the pH is lower than 4.

Q12. (Points: 4) - Discuss your value of the methyl red pKa and compare it with a published literature value what is the pKa, what does it represent and so what does this value tell you about methyl...

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