Can you please help me with the first two questions ? It would be amazing if you
ID: 486929 • Letter: C
Question
Can you please help me with the first two questions ? It would be amazing if you can also help me out with the third question as well.
1. Assume the range of concentrations of the unknown acids is between 0.40 M and 0.60 M. Ifa 5- mL aliquot is titrated with 0.20 M NaOH, what equivalence volume would you expect ifyou had the most dilute unknown? What volume of NaoH would you expect if you were assigned the most concentrated unknown? 2. How will the equivalence point volumes differ if you titrate the two solutions in Question 1? Explain your answer. 3. In carrying out the titration with a pH meter (not an indicator) what would you observe with respect to the pH as your titration approaches the equivalence point?Explanation / Answer
Acid + Base ---> Salt + H2O
1) a)Answer; The unknown acid most diluted concentration = 0.4 M
volume = 5 mL
Assuming that this acid is a monobasic strong acid
no. moles of acid = volume x molarity of acid = 0.005 x 0.4 = 0.002 moles
volume of base NaOH required to neutralize the above acid = (no. of moles of base)/ Molarity of base
at equivalence point no. of moles of base = no. of moles of acid
therefore ;
volume of NaOH = 0.002/0.2 = 0.010 L = 10 mL
b) Similarly; The unknown acid concentrated solution = 0.6 M
volume = 5 mL
no. moles of acid = volume x molarity of acid = 0.005 x 0.6 = 0.003 moles
volume of base NaOH required to neutralize the acid = (no. of moles of base)/ Molarity of base
at equivalence point no. of moles of base = no. of moles of acid,
therefore;
volume of NaOH = 0.003/0.2 = 0.015 L = 15 mL
2) The equivalence point will reach faster (consumes 10 mL of NaOH) for diluted acid solution, where as for concentrated solution it will consume 15 mL of 0.2M of NaOH. stronger the acid, more base is
needed to neutralize the acid.
3) when you do the titration using pH meter, you observe a sharp inclination of pH at the equivalence point.
Above this point, there will be more OH- ions, so the solution will be basic and pH will be greater than 7.
The equivalence point occurs at the point where very small additions of titrant cause a very rapid rise in the pH.