RoadChem — MyChemLab-style Virtual Chemistry Lab

Lab 7: Acid-Base Titration

Step 4 of 8

32:14 elapsed

Virtual Lab Bench -- Acid-Base Titration

NaOH 0.1M
24.6 mL used

HCl solution
+ indicator

Waste beaker

24.82 g

Analytical Balance

Hot plate (OFF)

22.4 C

Current pH

6.8

Indicator: turning

Add 0.5 mL NaOH

Add 0.1 mL NaOH

Swirl Flask

Record Data

Lab InstructionsStep 4/8

Procedure

Data

Analysis

Safety

✓

1. Record the initial mass of the HCl sample on the analytical balance.

✓

2. Dissolve the HCl sample in 50 mL of distilled water in the Erlenmeyer flask.

✓

3. Add 3 drops of phenolphthalein indicator to the flask.

4. Slowly add 0.1M NaOH from the burette while swirling the flask. Watch for a persistent pink color change.

Tip: Near the endpoint, add NaOH in 0.1 mL increments. The pH is currently 6.8 -- you're getting close!

5. Record the final burette reading at the endpoint (persistent pink for 30 seconds).

6. Calculate the volume of NaOH used.

7. Calculate the molarity of the HCl solution using M1V1 = M2V2.

8. Complete the post-lab questions and submit your lab report.

Lab Data -- Trial 1

Mass of HCl sample

0.842 g

Initial burette reading

0.00 mL

Current burette reading

24.6 mL

Current pH

6.8

Temperature

22.4 C

Final burette reading

Volume NaOH used

Molarity of HCl

Safety Reminders

NaOH is corrosive -- wear goggles and gloves. If spilled, flush with water immediately. Phenolphthalein is an irritant -- avoid skin contact. Dispose of all solutions in the waste beaker, not the sink.