2. Using your answer to question 1 calculate the theoretical and percent yields

Question

2. Using your answer to question 1 calculate the theoretical and percent yields for your product? l. Balance the following reaction equation. Note: in organic Chemistry, a standard balanced reaction equation not only balances all the elements on the left vs. the right, but also shows molecular structures. Formulas such as "CsHiso2" are normally not used, because they don't identify a specific isomer. t 2 HCI CHri clz t2 H20 H18 92 HCI OH conc, HCI 2H20 HO 2. Complete the following table, using your actual measured amounts. Greyed-out cells do not need to be filled. Mw(g/mol) conc (M) vol. mass mmol equivalents mp (mL) (mg) COC) 2,5-dimethylhexane- 146.23 2,5-diol HCl(aq) 2.00 183.12 2,5-dichloro-2,5- 60-fl 267.8 44624 dimethylhexane (crude) 183.12 2,5-dichloro-2,5 63-A o.350 dimethylhexane (recrystallized) 3. Describe the results of your chemical tests: a) Finkelstein (sodium iodide/acetone) test: No Precipitate b) AgNO3 test: Mil

Explanation / Answer

2,5-Dimethylhexane-2,5-diol is the limiting reactant as the other reactant namely HCl is taken in excess and the reaction can proceed only till complete consumption of the diol. Hence, theoritical yield should be calculated based on amount of 2,5-Dimethylhexane-2,5-diol taken for the reaction.

Theoritically 1 mole of diol leads to formation of 1 mole of the required dichloro derivative.

Since, 1.7760 mmol of diol is employed for reaction, 1.7760 mmol of the required dichloro derivative will form theoritically.

Theoritical yield of 2,5-dichloro-2,5-dimethylhexane is,

1.7760 mmol or 1.7760 * 10-3 mol * 183.12 g/mol = 0.3252 g  or 325.2 mg           

(since, mass = number of moles * molar mass;    1g = 1000 mg)

To Calculate Percent Yield

(i) For crude yield

Percent yield = (experimental yield / theoritical yield) * 100

Crude yield = 267.8 mg;     Theoritical yield = 325.2 mg

Percent yield = (267.8 / 325.2) * 100 = 82.3%

(ii) Percent yield of purified sample

Yield of recrystallised product = 70.5 mg;    Theoritical yield = 325.2 mg

Percent yield = (70.5 / 325.2) * 100 = 21.7%

ANSWER:

Theoritical yield = 325.2 mg

Percent yield of crude product = 82.3%

Percent yield (of purified or recrystallized product) = 21.7%

NOTE:

1.Unless otherwise mentioned Percent yield means percent yield of purified product.

2. Percent yield of crude product may be useful if amount of impurities is negligible. Percent yield of crude product is usually considered when the product is unstable under conditions of normal purification procedures; and the product is a starting material for next reaction step.

3. Percent yield of recrystallized product may be increased by obtaining more recrystallized product using the filtrant for further rounds of recrystallization.

4. Error in Percent yield may be minimized by proper extraction and drying techniques.

Related Questions

Navigate

• Browse (All)
• Browse 2
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.