ost Lab Questions the following questions in your discussion. What is the purpos
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ost Lab Questions the following questions in your discussion. What is the purpose of calibrating a pH meter? For the first part of this experiment, a sodium hydroxide solution was created and standardized If no NaOH was available to create a standardized basic solution, could another base such as potassium hydroxide (KOH) be used instead? What would be the consequences of using a nswer 1. 2. different base? Does it matter how much water was used to dissolve the KHP? Why or why not? 3. a. Does it matter whether the grams of KHP was accurately measured? Why or why not? If you had substituted a Ca(OH)2 solution of the same molarity and titrated the same unknown HCI solution, how would the volume of Ca(OH)2 necessary to reach the equivalence point be different than that of the NaOH solution? HINT: How many OH ions are produced with Ca(OH)2 versus NaOH? How would your results be different if the unknown HCI solution in part 2 was measured with a graduated cylinder instead of a volumetric pipet? For both parts of the experiment, why was it necessary to perform each titration three times? 5. 6. a. Why was it important to continue the titration past the equivalence point? b. Why was it important to control the drops from the buret when using the drop counter? Why would a steady stream cause you to start over? How would your results be different if you placed the unknown HCI solution in the buret and placed the standardized NaOH solution in the beaker How does the precision required for Part 1 differ from that of Part 2? What are some sources of errors that are associated with both parts of the experiment? How can you prevent these errors? 7. 8. 9.Explanation / Answer
1) the Purpose of calibrating a pH meter is to make if error free
2) There will not be much effect on changing NaOH with KOH, as both are strong base. However we can consider that the dissociation of KHP may be decreaseds due to common ion effect furnished by KOH .So it is advisable to use NaOH .
3) The amount of water used to dissolve KHP will not affect the actual experiment, as number of moles / gram equivalents will be same if the amount of KHP is same.
b Yes. the accurate measurement of mass of KHP is required as the amount of KHP will give determine the number of gram equivalents produced
4) Each mole of Ca(OH)2 will give two moles of Ca(OH)2 while only one mole will be produced by one mole of NaOH.
5) The volume of HCl used will not be accurate,so the number of moles will also be different
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