Preparing the NaOH Solution In this experiment KHP is a primary standard. Define
ID: 961863 • Letter: P
Question
Preparing the NaOH Solution In this experiment KHP is a primary standard. Define primary standard. What substance, commonly found in air, will react with sodium hydroxide solutions, causing them to decrease in concentration? Considering your response to the previous question, why is it necessary to use a primary standard, such as KHP, to determine the molarity of sodium hydroxide solutions? In this experiment, sodium hydroxide is weighed, then dissolved and diluted to 250 ml in a volumetric flask. Using your data from Table 2, calculate the approximate molarity of the sodium hydroxide solution. Show your work in the space below. Compare the value calculated in previous question with the average molarity of the sodium hydroxide determined by titration. Which is likely to be more accurate? Why?Explanation / Answer
3 )
primary standard concentration is fixed that does not change with time . if we use another titratnt which is not primary standard its concentration changes with time due its nature hygroscopic etc we get false value for unknown compound. in order to get correct molarity of unknown we need to use primary standard
4)
mass of NaOH = 1.032 g
molar mass = 40 g/mol
moles = 1.032 / 40 = 0.0258
volume = 250 mL = 0.250 L
molarity = moles / volume
molarity = 0.0258 / 0.250
= 0.1032 M
5)
prevoiusly you calculated the value of NaOH . compared that value with 0.1032 M
by experiment calculated value is more accurate than 0.1032 M value . it is due to NaOH is not primary standard . it catches water from atmospher so its volume increases and moalrity decreases. 0.1032 M is not accurate molarity of NaOH .