lab name:Ester Synthesis Hints for answering above questions (some calculations)
ID: 533570 • Letter: L
Question
lab name:Ester Synthesis
Hints for answering above questions (some calculations)
(1 pt.) Assuming all of the alcohol is consumed in your reaction, how much acetic acid would you expect to remain unreacted? Explain your reasoning in one very short sentence. 5. (1 pt.) Let's assume that you have 0.001 moles of sulfuric acid at the start of your reaction? Roughly how much sulfuric acid will you have at the end of the reaction? Explain your reasoning in one very short sentence. 6. (2 pts.) The reagents/conditions are sulfuric acid and heat. Both are present to ensure that the reaction finishes in a reasonable amount of time (i.e. you don't have to wait all day for it to finish). How does EACH of them help to ensure that the reaction is completed in a reasonable amount of time? 7. (2 pts.) As you showed above, either the acid or the alcohol is on EXCESS (i.e. is not limiting). Having one of these in excess also helps the reaction to finish in a reasonable amount of time, how does it do that? 8. (3 pts.) One of the reasons that sodium hydroxide is not used in the extraction of the acids is that it may react with the ester. The mechanism of reaction of sodium hydroxide and a generic ester is shown below. Add the missing curved arrows, AND, for each INTERmolecular step (each step that involves a reaction between two molecules), indicate whether the reactants are a Lewis base or a Lewis acid (use the abbreviations LB and LA), AND, whether the reactants are BRONSTED acids or bases (use LA and BB) ONa H20 Na EO-R H3C O H H3C-C H3C 9. (1 pts.) What is the purpose of adding sodium sulfate at the end of your procedure? Give a 1 sentence explanation that includes at least a mention of INTERMOLECULAR FORCES u can check previous lab packages for help with this question) 10. (1 pt.) What is the purpose of refluxing this reaction? Give a 1 sentence explanation that includes the word energy 11 (2 pts.) Define the word "catalyst," is a catalyst consumed in a reaction?Explanation / Answer
Answer to Q4)
The esterification reaction is given as:
ROH + CH3COOH <--------> CH3COOR + H2O
From the above reaction we know that 1 mol of alcohol reacts with 1 mol of acetic acid
Acetic acid required for the reaction = 0.013 mol
Excess acetic acid (left unreacted) = Number of moles of acetic acid added - Number of moles of acetic acid required for the reaction
= 0.067 -0.013 = 0.054 mol
Mass of acetic acid left unreacted = number of moles of excess acetic acid X Molar mass of acetic acid
= 0.054 mol X 60.05 g mol-1
= 3.2427 g
Answer to Q5)
Sulfuric acid catalyses this reaction and does not take part in the reaction. Hence, at the end of the reaction the amount of sulfuric acid will remain unaltered and we will have 0.001 mol of sulfuric acid.
Answer to Q6)
Esterification reaction is slow and reversible at room temperature. Addition of concentrated sulfuric acid can provide alternate pathway to the forward reaction with much lower energy of activation. Refluxing the reaction mixture can help to reach the activation energy quickly. Thus heat and concentrated sulfuric acid can speed up the reaction. Additionally, concentrated sulfuric acid also acts as a desiccating agent thus preventing backward reaction and producing more ester.
Answer to Q7)
Esterification reaction is slow and reversible. Thus for the equilibrium to shift to right and favour more ester, one of the starting reactants must be used in excess.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.