General Chemistry
Faculty of Allied Medical Sciences
(MGGC-101)
Supervision:Prof.Dr.Shehata El-Sewedy
Dr.Fatma Ahmed
Limiting reagent, theoretical
and percent yield
Outcomes By the end of this lecture, the
students will be able to1-Understand the Limiting Reagent
2-learn to excess reactant of the reactions3-To differentiate between theoretical and
percentage yield 4-Recognize actual yield
Limiting Reagent
The limiting reagent (or limiting reactant): is the reactant which is completely consumed in the reaction. The other reactant will be in excess. For example
Limiting Reagents
3.9
2NO + 2O2 2NO2
NO is the limiting reagent
O2 is the excess reagent
Example Zinc metal reacts with hydrochloric acid by the following reaction:Zn(s) + 2 HCl(aq) ZnCl2(aq) + H2(g)If 0.30 mol Zn is added to hydrochloric acid containing 0.52 mol HCl, how many moles of H2 are produced?
Answer:Take each reactant and calculate how much product would be obtained if each were totally consumed. The reactant that gives the smaller amount is the limiting reagent. Zn
H2
1 mole I mole
0.30 mole X ?
X (no of moles of H2) = 0.30 mole.
similarly:2 HCl H2
2 mole I mole
0.52 mole X ?
X (no of moles of H2) = 0.26 mole.Since HCl is the limiting reagent, the amount of H2 produced must be 0.26 mol. Zinc is the excess reactant.
Example 2SO2(g) + O2(g) + 2H2O(l) → 2H2SO4(aq) How much H2SO4 can be formed from 5 moles of SO2 and 2 moles O2 and unlimited quantity of H2O ?
Answer SO2 : 2H2SO4
2 : 25 X mol
5 moles of SO2 will give 5 moles of H2SO4, while O2 : H2SO4
1 : 22 X
H2SO4 formed = 4 moles2 moles O2 will give 4 moles of H2SO4 . O2 is the limiting reagent
Theoretical and Percent Yield•The theoretical yield of product is the maximum amount of product that can be obtained from given amounts of reactants.•The percentage yield is the actual yield (experimentally determined) expressed as a percentage of the theoretical yield (calculated).
%100yield ltheoretica
yield actual Yield%
Example 2C6H12 + 5O2 2H2C6H8O4 + 2H2O cyclohexane adipic acid Assume that the reaction start with 25gram cyclohexane which is the limiting reagent.a-What is the theoretical yield of adipic acid. b- If you obtain 33.5gram adipic acid calculate the % yield .
Answer 2C6H12 2H2C6H8O4
2moles : 2 moles 2(mol. mass) 2(mol.mass) 2X 84 2X 146 25g X g Grams adipic acid = 2 146X25/2X84 = 43.45 grams. a- Theortical yield = 43.45gram. b- % yield = (33.5 / 43.45) 100 = 77.1%
Quiz time
Zinc metal reacts with hydrochloric acid by the following reaction:Zn(s) + 2 HCl(aq) ZnCl2(aq) + H2(g)If 0.30 mol Zn is added to hydrochloric acid containing 0.52 mol HCl, how many moles of H2 are produced?
2SO2(g) + O2(g) + 2H2O(l) → 2H2SO4(aq) How much H2SO4 can be formed from 5 moles of SO2 and 2 moles O2 and unlimited quantity of H2O ?
2C6H12 + 5O2 2H2C6H8O4 + 2H2O cyclohexane adipic acid Assume that the reaction start with 25gram cyclohexane which is the limiting reagent.a-What is the theoretical yield of adipic acid. b- If you obtain 33.5gram adipic acid calculate the % yield .
Student Question
Define
Limiting Reagent
Theoretical yield
Percentage yield
2C6H12 + 5O2 2H2C6H8O4 + 2H2O cyclohexane adipic acid Assume that the reaction start with 25gram cyclohexane which is the limiting reagent.a-What is the theoretical yield of adipic acid. b- If you obtain 33.5gram adipic acid calculate the % yield .
Assignments(1)Group A and Group B
Hanan Ahmad Zaid -Alfa Magdi - Alaa Kamal Anani – Asmaa Mohamad El-Awadi- Sara Ali Abd El-Latif- Alaa Emad El Din – Eisha Youssef
Nitrous acid
Hagar Saeed – Shrouk Abd El-Aziz – Mona Ashraf Ramadan – Nahed Atia –Mai Mahmoud-Haidy Mahmoud – Walaa Ebada
NMR spectroscopy
Eman Gamal- Mona Ashraf Kamal- Fahd Abd El Salam-Mohamad Montaser-Wasal Mohamad
Uses of Gases in industry
Asmaa Gamal-Mahmoud Ezzat-Shady Ahmad-Taha Mohamad Nasri - Eisha Ali
Mass spectroscopy
Assignments(2)Group A and Group B
Hend Nazmy – Heba Waheed – Hagar Eman Gamal - Adel
Addition reaction
Mostafa Ahmad Shata – Abd El Rahman Ali-Mohamad Magdi- Motasem Abd El-Aal
Combination reaction
Mohamad Mahmoud Awad-Marwa Ahmad-Sara Emad –Mariam Hamdy
Application of nitric acid
Marina Maged-Nourhan Emad-Engy Roshdy-Madonna Micheal-JosianIsaq-Merna Farag Allah-Christin Magdi-Verona Romani-Makarious Maher-Mena Malak
Theoretical yield
Assignments(3)Group A and Group B
Eman Gamal- Mona Ashraf Kamal- Fahd Abd El Salam-Mohamad Montaser-Wasal Mohamad
Solution
Kholod El-Said – Riham Hassan – Esraa Hafez-Asmaa Basha –Asmaa Mohamad Hassan-Dina Nassem
Chemical equilibrium
Ibrahim Abd El Aatti-John Micheal-Bishoy Sadeek
Application of Hydrochloric acid
Mariam Thrwat- Kyrillos Rafaat – Mina Kabeel-Fadi Abd El Salam
Uses of Helium
Khaled Eid- Sameh Raafat- Bishoy Shanoda-Sobhy Sabry-Ahmad Saeed Shehata-Abd El Rahman Abd El Aziz-Ahmad Zian-Mohamad Waheed
Gases
ASSIGNMENTS(4)
Group A and Group B
Someya Mostafa – Maram Ahmad – Esraa Mahmoud
Poisonous Inorganic substances
Youssef AboBakr – Mina Melad – Omar Gamal Kamal
Uses of Noble gases
RECOMMENDED TEXTBOOKS:
1-Raymond Chang. Chemistry. 10th ed. 20092-Zumdehl. International edition. 2009
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