Pre-lab Exp 2 DK014

Choose the correct formula for molarity

• Molarity (M) = moles of solute / liters of solution
• Molarity (M) = moles of solvent / liters of solution
• Molarity (M) = grams of solute / liters of solution
• Molarity (M) = moles of solute * liters of solution

Addition of distilled water into volumetric flask should be done carefully. What should you do if you overfilled the flask with water above the graduation mark?

• Shake the flask vigorously to mix the excess water
• Ignore the excess water and proceed with the experiment
• Pour out excess water until the meniscus is at the graduation mark.
• Discard the content of the flask, rinse and start the measurement process again.

Explain the action taken by the person in the picture to avoid overfilling of distilled water into the volumetric flask.

• Adding distilled water drop by drop using a dropper

• Blowing air into the volumetric flask
• Shaking the volumetric flask vigorously
• Pouring the distilled water quickly from a beaker

Based on the picture shown, what is the initial and final burette reading?

• Initial reading: 1.80 mL, Final reading: 23.80 mL

• Initial reading: 0.00 mL, Final reading: 22.00 mL

• Initial reading: 0.20 mL, Final reading: 22.20 mL

• Initial reading: 5.00 mL, Final reading: 23.50 mL

What precaution should be taken based on the image provided?

• Adjust the burette so the meniscus is at eye level.
• Tap gently or discard some solution in the burette to remove air bubble at the tip.

• Shake the burette vigorously
• Use the burette without adjusting

Which of the following conical flask shows the titration has reached it's end point?

• Left

• Right

Based on the diagram shown, what is the volume of HCl dispensed?

• 20.00 mL

• 21.50 mL

• 23.20 mL

• 22.00 mL

What is the average volume of HCl dispensed?

• 12.50 mL

• 12.40 mL

• 12.47 mL

• 12.48 mL

How to ensure that you will get an accurate final end point?

• Titrate quickly.

• Repeat the titration 3 times.

• Do not rinse the burette.

• Always use the same pipette filler.

Why it is important to rinse the unreacted solutions at the inner wall of the conical flask with distilled water (Step number 7 in Experiment 2 Part B lab manual) ?

• To help the reaction go faster.

• To dilute the reagents.

• To ensure accuracy (all solution reacts).

• To see the colour of the indicator better.