Lab 4: Acid/ Base Titration 4.1: Preparation and Standardization of NaOH with KH

Question

Lab 4: Acid/ Base Titration 4.1: Preparation and Standardization of NaOH with KHP in this experiment, Potassium Hydrogen Pthalate (KHP- KCHs0) will be used as the primary standard to In this ex standardize the NaOH solution KOH Phthalic Acid Potassium Hydrogen Phthalate (HP) The net ionic equation for the titration is: H2O Possible Sources of Error: Reading Errors: It is easy to read the balance or the buret wrong. Check each reading carefully - Alkaline solutions absorb carbon dioxide from the atmosphere according to the reaction: OH Since hydroxide ion is consumed by this reaction, the concentration of a standard sodium hydroxide o solution will be changed. Precautions must be taken to protect the standard alkali solution from the carbon dioxide that is always present in the atmosphere. During titration the sodium hydroxide in the buret is exposed to air, therefore the buret SHOULD NOT be prepared for use until it is needed, and fresh sodium hydroxide should be added if it has stood in the buret for more than about 20 minutes NEVER TAKE MORE NaOH FROM THE BOTTLE THAN IS NEEDED FOR ONE TITRATION Take only as much NaOH as is needed to fill or refill your buret. Tap water and even distilled water may contain dissolved carbon dioxide. To remove the CO, water may be boiled. 10

Explanation / Answer

sample 1:

              concentration of KHP is = VB * SB / VA = .137 M

where VB = VOLUME OF BASE NAOH

VA = VOLUME OF ACID KHP

SB = STRENGTH OF BASE NaOH

M.W OF KHP = 204 g/ mol

amount of KHP In 250 ml sample = 204 * .137 /1000 * 250 = 7 gm

triter vaule have some error may be.

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