CHEM 01LA Lecture Notes - Lecture 5: Molar Mass, Equivalence Point, Titration

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20 May 2018

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CHEM 01LA Experiment 5: Molar Mass of a Solid Acid

●Experimental Purpose

○The purpose of this experiment is to titrate an unknown, organic acid with a

NaOH solution of known concentration to determine its molar mass

●Acids

○Acid: a substance that produces hydrogen ions (protons



) when dissolved in water

■Monoprotic: contains one acidic proton

■Polyprotic: contains more than one acidic proton

●Molar Mass

○Molar mass: the mass (in grams) of one mole of the compound

■Presence of more protons does not necessarily indicate a significantly

larger molar mass

●Acid-Base Titrations

○Equivalence point: the point in the reaction at which the number of moles of H+

furnished by the acid exactly equals the number of moles of OH- furnished by the

base

■Moles of H+ = Moles of OH-

●Moles of OH- = [OH-] x Volume OH-

○Moles of H+ = [OH-] x Volume OH-

○Indicator: visualizes the end point of a titration by changing color at or near the

equivalence point

○End point: the point at which the titration should be stopped

●Notes

○Appendix D (operation of burets and performance of titrations) should be read

prior to lab

○Wear safety goggles: acids and bases are hazardous to eyesight

○Study experiment prior to lab day: it will be long if background knowledge is not

absorbed

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Document Summary

Chem 01la experiment 5: molar mass of a solid acid. The purpose of this experiment is to titrate an unknown, organic acid with a. Naoh solution of known concentration to determine its molar mass. Acid : a substance that produces hydrogen ions ( protons ) when dissolved in water. Polyprotic : contains more than one acidic proton. Molar mass : the mass (in grams) of one mole of the compound. Presence of more protons does not necessarily indicate a significantly larger molar mass. Equivalence point : the point in the reaction at which the number of moles of h + furnished by the acid exactly equals the number of moles of oh - furnished by the base. Moles of h + = moles of oh - Moles of oh - = [oh - ] x volume oh - Moles of h + = [oh - ] x volume oh -

Related Questions

advance study assignment molar mass of an acid.
1. 7.2ml of 6.0M NaOH there are in 7.2ml of 6.0 M NaOH are diluted with water to a volume of 400.0ml. you are asked to find the molarity of the resulting must be solution.
a. first find out how many moles of NaOH there are in 7.2ml of 6.0 M NaOH. use equation 1. note that the volume must be in liters.
b. since the total number of moles of NaOH is not changed on dilution, the molarity after dilution can also be found by equation 1. using the final volume of the solution. calulate the molarity.
2. in an acid base titration, 21.16ml of an NaOH solution are needed to neutralize 20.04ml of a 0.0997M HCL solution. to find the molarity of the NaOH solution, we can use the following procedures.
a. first note the value of MH+ in HCL solution.
b. find MOH- in NaOH solution equation 3
c. obtain M NAOH from M OH
3. a 0.3012g sample of an unknown monoprotic acid requires 24.13ml of 0.0944 M NaOH of neutralization to a phenolpthalein end point. there are 0.32ml of 0.0997 M HCL used for back titration.
a. how many moles of OH- are used?
how many moles of H+ from HCL?
_____moles OH- _______ moles H+
b. how many moles of H+ are there in the solid acid? use eq 5.
____moles H+ in solid
c. what is the molar mass of the unknown acid? use equation 4.
______g/mol