Question

64 Experiment 9 Titration of an Acid with a Base QUESTIONS PRE LAB 1. How would the calculated concentration of the HCl be affected, if the sodium hydroxide were poured from a beaker that contained some water before the NaOH were added to it? 2. What color is phenolphthalein in acid? What color is it in base? 3. The acid and base in this experiment are completely harmless-True or False? Explain your answer.

Answer 1

1] If the sodium hydroxide beaker contains some water before it was added to HCl then the calculated concentration of HCl will be more than the theoretical value. because if sodium hydroxide contains water then the concentration of NaOH will become less and the volume of HCl required to neutralize the NaOH will be less. As the volume of HCl required is less then from  dilution equation the concentration of HCl will be more.

2] In Acid media phenolphthalein will be colorless. In Basic media phenolphthalein will have pink color. phenolphthalein is an acid base indicator and it will be used during acid-base titration to indicate endpoint.

3] False. Because concentrated HCl (Hydrochloric Acid) is corrosive in nature and also NaOH (Sodium Hydroxide) will causes thermal burn. but if they are used in diluted version & also in small amount then they are some what harmless.

Answer 2

1] If the sodium hydroxide beaker contains some water before it was added to HCl then the calculated concentration of HCl will be more than the theoretical value. because if sodium hydroxide contains water then the concentration of NaOH will become less and the volume of HCl required to neutralize the NaOH will be less. As the volume of HCl required is less then from  dilution equation the concentration of HCl will be more.

2] In Acid media phenolphthalein will be colorless. In Basic media phenolphthalein will have pink color. phenolphthalein is an acid base indicator and it will be used during acid-base titration to indicate endpoint.

3] False. Because concentrated HCl (Hydrochloric Acid) is corrosive in nature and also NaOH (Sodium Hydroxide) will causes thermal burn. but if they are used in diluted version & also in small amount then they are some what harmless.