Question

Q1:

• In part A you will prepare a dilution solution of 0.1M NaOH using a 500mL graduated cylinder and pump dispenser.
• The solution is then mixed and stored in the amber bottle found in your drawer.
• Be sure the cap is in good condition.

Calculate the volume of 6.0M NaOH needed to make 450 mL of about 0.7 M NaOH. Do not include units in answer.

Q2:

After the first trial, in order to maximize the titration precision, the sample size of pure KHC₈H₄O₄ or unknown for a trial should be adjusted so 20-23 mL of NaOH are delivered in both part B and C. This can be done as noted in your lab manual.
If 7.25 mL NaOH was used in the titration of a 0.465 g sample use ratios to determine mass of sample needed to use 22.00 mL of NaOH in the next trial.

Q3:

Put the following steps in a titration in the correct order. Number 1-7 .

a)Add titrant to sample solution in flask rapidly and slowly when approaching end point.
b)When a light pink stays for at least 30 seconds take a buret reading and double check.
c)Fill buret with titrant to above zero and rapidly let titrant out to remove air bubbles.
d)Rinse the inside walls of the flask just before the end point.
e)Refill buret for next trial or rinse buret several times with tap water and once with distilled water if done for the day.
f)Rinse the clean buret twice with the titrant and drain completely.
g)Refill if needed to between 0-1 mL, take buret reading and double check reading.

Answer 1

Q 1:

Required volume =Final concentration of NaOH * Final Volume of NaOH solution / Initial concentration of NaOH = 0.7 M * 450 mL / 6.0 M = 52.5 mL

Answer is : 52.5

Q 2:

Mass of the sample required = 0.465 g * 22 mL/ 7.25 mL = 1.41 g

Q 3:

f)Rinse the clean buret twice with the titrant and drain completely.

c)Fill buret with titrant to above zero and rapidly let titrant out to remove air bubbles.

g)Refill if needed to between 0-1 mL, take buret reading and double check reading.

a)Add titrant to sample solution in flask rapidly and slowly when approaching end point.

d)Rinse the inside walls of the flask just before the end point.

b)When a light pink stays for at least 30 seconds take a buret reading and double check.

e)Refill buret for next trial or rinse buret several times with tap water and once with distilled water if done for the day.