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Free Chemistry Help
I provide Free Chemistry Help upto High School Level. Just place your questions at the Free Chemistry Help Forum and they will be answered in no time.
Chemistry Quizzes
 I provide Practice questions in Chemistry to the students on this website. Detailed quizzes with answers have been compiled for all the courses offered here. For Chemistry Quizzes, please click here.
Useful Resources

Important Chemical Reactions

Displacement Reactions and Net Ionic Reactions
What My Students Have to Say

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My exams had gone off so well after my sessions for MCAT exams with you. I have thoroughly understood Aromatic Reactions, Alkenes and Alkynes after studying with you. Thank you so much. You are the best Chemistry Tutor I have ever had.

Yashika Patel, Boston(MCAT )

You are the best tutor that I have come across in my life. Keep up the good work.

Nick(MCAT)

Dear Uma, We want to thank you for the all hard work you did teaching Felix chemistry: Thanks to your dedicated tutoring he was able to score 760 on his Chemistry SAT test . We are very happy with the test results.

Alex and Katrina Glozman (parents of SAT/AP/general chemistry)

Hi Uma
I got my sat score today. I received a 760 for chemistry. Thank you very much for all your teachings.Under your guidance I will be successful in chemistry..

Felix(SAT Chemistry)

My wife and I will like to thank you for helping our son do so well at AP Chemistry. Although he got a 4, given where you picked him up and the total lack of teaching in his school, the exam outcome was a realistic one.
Mrs. Sharma. my son holds you in very high regard. He describes you as "One of the best teacher in the World " and he says so with a lot of conviction.
As parents we are grateful to you for helping him change his attitude to Chemistry from total fear and intimidation to love for the subject.

Mr P Maitra(Father of AP chemistry student)

Wanted to let you know that Mallika got a 5 on her AP Chemistry exam. Thank you for your efforts.

Radhika Madhusudan mother of AP student

Hello Uma, I just want to let you know that I got accepted to Midwestern University- Chicago College of Pharmacy (my preference) and I also received an invitation to interview at University of Illinois at Chicago College of Pharmacy as well! Both of these schools are the best in my area. I am beyond excited and overjoyed. Of course, it would not have been possible without your assistance and support in organic chemistry. My professors thought that I should pursue advanced organic chemistry or even PhD's- they did not know I worked with a great tutor by my side and that it had made all the difference for me to have met you. My success in my organic chemistry class spilled over to other science classes that I took. I plan to continue working hard and perhaps, very soon, I will need another session with you! Thank you very much again! Sincerely, Cat

Catphuong Nguyen(pharmacy student)

Dear Dr. Sharma, I want you to know that I see you as a mentor. So far, in my life, it has been my mentors who have really helped me, guided me, and I know will mold me even beyond the scope of my career. I will always remember to thank you for all you do. Thank you for all of your help and guidance, Dr. Sharma. Hope you feel better and I will get Sitopladi and Honey :) Kindest Regards, Vinay Sehgal

Vinay Sehgal (organic chemistry student)

Hello Uma, Thank you for your session this morning. My daughter said it was very informative and she learnt well. She said she liked the fact that you asked her questions. Please make sure she understands her basics well, even if it takes more of your time. I have bought a package for 5 hours. As discussed this morning, please schedule the lesson for 8:00 -10:00 am EST tomorrow 3/5. Thank you again for your time and efforts. Vidya

Vidya (mother of Deepika organic chemistry student)

I got my scores-in general chemistry my correct answers were 26 out of 30 questions so my DAT score is 20 out of 30. in organic chem my correct answers were 23 out of 30 questions so my DAT score is 19 out of 30. my average DAT score is 19 out of 30...not bad. we have to see what is the cut off of new york university. it shoud be around 18 or 19 or 20..according to the office people in the university. will come to know in 2013 spring thanks to you for everything..Icouldn't have scored even this much without your help. The overall exam was not that easy..there were some pretty hard questions.specially the PAT section was quite hard when I travel to india this december I will get all the DAT books for you. barrons,kaplan,dat destroyer. thanks again ,will talk when u are free. I was called for interview. will get the result on 3 weeks

Jaspreet (DAT student)

hello uma ji, The cut off of DAT at the new york university has gone down to 17. i have a score of 19 . still waiting for my result. my application got submitted after the deadline due to some reasons. but hoping for the best. hope you are still rocking at ur lectures and wishing you luck as always

Jaspreet(DAT student)

Hi I am Shah here.I am taking regular tutoring from chemtopper for organic I from uma sharma(tutor).Today I appeared in my final examination and my professor just scanned my answers and told me to get enroll in organic II .This is never heard in USA that a professor asking a student to join a course like this.I think this is something awesome in a student's career .I am really thankful to chemtopper and specially to Uma Sharma (my preferred tutor) who really helped me a lot during my examination time.She helped me understanding organic chemistry in much simpler way by her unique way of teaching.I would like to continue with her as my preferred tutor for organic chemistry II.

Shah (2009)(organic chemistry student)

I had been a novice at Chemistry when I joined Organic Chemistry-I. In my first exam I had got ‘F’ grade and was on the verge of leaving Organic Chemistry when I found you. You have made Organic Chemistry so simple for me. I am now the topper of my class having scored 100% in my exams !!!

Kim Dewitt(organic chemistry student)

In my DAT I was in the top 93 percentile of the US for that section, which means I scored higher than 93% of all test takers. it was all thanks to you Can't tell you how much you helped.

Neha Garge(DAT student)

Hello I would like to thank a very articulate tutor Miss Uma Sharma specifically for helping me with Organic chemistry. Her knowledge of subject is amazing. The way she deals with the topics reveals her deep understanding of the subject. Her encouragement to delve deeper into the subject keeps me flocking into her session. She helps me understand my assignments well so that i am able to work independently. She was never lost for words when questioned, and i always had answers. Miss Uma Sharma is indeed an asset as a tutor. I praise her dedication and genuine love for her profession that was evident in the way she taught.

SHAH Colorado, USA(organic chemistry)

Ms.Uma was very helpful. The active teaching when she asks the student gives the student practice and ensures their understanding which I found helpful.

Neije(Moitreyee)IB student

Uma, Qian transfer from 11th grade to 12th grade on chemistry subject, she was assessed 2 days ago. When I got the news, I want to thank you again for being a very good chem teacher.

Helen( Quian's mother)

I was so happy when I heard my daughter passed AP Bio & Chem both with 4s. Her effort has paid off. I credit Chemtopper for tutoring her. My daughter's school wasn't able to offer AP classes, and I wasn't able to find tutors who taught AP in English in China, so I turned to online AP courses, and I found Chemtopper. Chemtopper's team is wonderful; both our Bio and Chem tutors are PhDs and very experienced tutors. We went through all the content in 3 months and passed the exams with satisfactory results.

Helen Feng(Qian's mother)

just to let you know that Aarti got an offer for a Pharmacy course in London ,King's colleges.She is very excited... she got all the offers from UK thanks for all yr help you gave to aarti she feels comfortable with chemistry

Renuka Patel(mother)

Really good. Tutor was well prepared and explained concepts by using different examples. The sessions are saved so they can be revised afterwards as well. ** HIGHLY RECOMMENDED **

Jamal Ahmed IB chem student

HI Uma ji, I got admission into DDS programme at NYU. Thanks a ton for helping me through and motivating me all the time I wish good luck to you . Your teaching will help make students with a strong foundation God bless you

Jaspreet (DAT student)

Dear Dr. Sharma, Would like to finish chapter 3 in tomorrow's session. I make sure to review notes after our sessions and then go back to re-read the Kaplan book. You are absolutely right: without a complete understanding of the topic, it will be very difficult to grasp the material. Thank you for helping me understand the material so thoroughly.

Vinay Sehgal (MCAT student ))

Dear Uma, My wife and I want to thank you once again for the excellent teaching that you provide to our younger son Thomas. Thanks to your dedicated teaching he, while still in 10th grade, was able to score a 5 in AP Chemistry. You helped him build a solid foundation in inorganic chemistry, and now continue to teach him organic chemistry. He is happy to be your student and we are happy you are his teacher. Sincerely, Ekaterina and Alex Glozman

Alex and Katrina Glozman (parents)

Hi Dr. Sharma, I'm reviewing Orgo Part 2. Everything you taught me is coming back very easily. Once again, thank you! Orgo is 25% of the Biological Sciences section and every point counts. Chemistry is 50% of the Physical Science section so I am making sure to keep up in that area too. Hope you have a safe trip. See you soon. Kind Regards, Vinay Sehgal

Vinay Sehgal (MCAT student ))

A great tutor who enjoys chemistry as well as teaching it. Her teaching style is very understandable and easy. Neither have i had such a good chemistry tutor or have I understood chemistry as much as i did before I started classes with Uma. Couldn't ask for a better chemistry tutor!

Sai Muttavarapu-2013

Great job teaching Organic Chemistry specifically mechanisms of reactions. Thank you.

Felix

After the session I finally understood resonance structures of organic compounds. This is a high yield topic on the MCAT. I wish my college professor could teach as well as Uma.

Felix

I'm in the IB program, and having these online sessions to review for my exams are perfect! Thanks a lot!

Dusan

Really good. Tutor was well prepared and explained concepts by using different examples. The sessions are saved so they can be revised afterwards as well. ** HIGHLY RECOMMENDED **

Jamal Ahmed

It's great that you are so patient in explaining things multiple times and giving extra examples to work out to make sure that I understand the points. Thanks for all your help!

Sunitha

Great session, I really like how you're challenged on your knowledge, it keeps you on your toes while learning - thanks!!

Trevor

very good lecture. mrs. uma know where to hit the chord

Jim

the lecture was awesome. never thought i could solve organic chemistry with ease . it has been made possible under the guidance mrs. uma sharma..a wonderful teacher who has a very fine understanding of the needs of her students .

Jaspreet

I can tell you, the help is so valuable. I was ranging from 74-82%, everything is 90+ now waiting for the chem marks to be posted from last week. amazing tutoring in chemistry

Trevor Poole

Hello ms. Sharma, I wanted to let you know that my ap chemistry exam on monday went extremely well. :) Thank you so much for all the tutoring and help you gave me. I am very pleased with your teaching.... I wish you were my chemistry teacher! My chemistry teacher here was recently diagnosed with ovarian cancer. This is the third time she has gotten the cancer back and there is no guarantee for recovery. But i am very grateful to have come across your website.... I have survived chemistry because of you. Your love for chemistry has inspired me to pursue biochemistry, since i realized through you chemistry is a subject to enjoy and love. Its not just about learning the concepts but actually enjoying them! I am 100% going to continue with your website and teaching for general chemistry and organic chemistry in college. I will have also recommended your website to lots of my friends here. Once again, and never the last, thank you so very much for helping me and guiding me through chemistry. I miss having your sessions at night (over here, for you its morning :). But i will definitely see you in the summer with some more tutoring to prepare me for college! Thanking you, Yours sincerely, Anusha Sent from my iPad

Anusha (AP chem student)

hello ms. sharma! i got my ap scores today and i made a 4 out of 5 on ap chemistry!!!! thank you so much ms. sharma for helping me understand and enjoy chemistry, not just only learning it. i was literally in tears when i saw my score. i have claimed credit for general chemistry I and i will be taking general chemistry II. i have not scheduled for my classes yet.... but i will definitely join chemtopper.com again for chemistry, math and physics. thank you so much ms. sharma....... and i will meet you very soon! yours sincerely, Anusha

Anusha (AP chem student)


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AP Chemistry Exam Date of Exam. 05 May 2014 Monday 8 A. M.

AP Exam Grades
The Students scores on the free-response questions are combined with the results of the computer-scored multiple-choice questions; the weighted raw scores are summed to give a composite score. The composite score is then converted to a grade on a 5 point scale:

AP Exam Gradings
Extremely Well Qualified
Well Qualified
3 Qualified
2 Possibly Qualified
No Recommendation
The Exam
The AP Chemistry Exam has two main parts
Section I - 90 minutes 60 Multiple choice questions (MCQs) Calculators are not permitted.
Total weightage  :   50%
MCQs are either discreet questions or sets of question, Questions are based on the knowledge of Chemistry and Science practices outlined in AP Chemistry course. Question sets are new types of questions in which a stimulus in the form data or series of questions will be provided. No negative  marking or no marks deducted for incorrectly answered questions. Score is based on the number of questions correctly answered.


Section II 
  90 Minutes Three long free response questions ,two short free response questions.Programmable or graphic calculators are permitted.

Total weightage   :      50%

Questions will be based on:
(1)   Experimental procedures, data, graphs observations and error analysis.
(2)   Explanation of phenomena based on molecular, atomic level of the matter   
(3)   Logical and analytical path ways to solve a problem.
Commonly used equations sheet will be provided with each exam for use. However in free response exam no marks will be awarded for simply writing the correct equations. No marks will be awarded for ambiguous answers without any reasonable explanations.

 

Use of Calculators in AP Chemistry exam.

Calculators are not permitted in section I and questions based on simple calculators will be the part of section I. Programmable or graphic calculators are permitted for the entire free response exam. Calculators will not be allowed to share and calculators with type writer style (QWERTY) keyboards will not be permittted
Study Packages

The study packages for AP Chemistry Exam have been designed to cover the complete AP syllabus for Chemistry. The package can be customized as per your requirements.

Study Material.
I use the relevant study material for AP Chemistry Exam for comprehension of the subject in detail. I use my own presentations which have been prepared keeping the requirements of the students in mind.

Chemistry Practice Quizzes .I also provide Chemistry Quizzes for AP Chemistry Exam which students can attempt in their own time and discuss with me during the sessions. Please feel free to Contact Me for any clarifications.

 Study Topics .The study topics which are covered in the AP Chemistry exam have been given out below.

Limiting reactant AP Chemistry Trial Quiz

Quiz : Limiting Reactants

 
Learning Objectives : 6 Big Ideas

Big Idea 1 : Structure of matter

 

1.1 States of matter, Laws of chemical combinations.Elements, compounds and molecules, Mixtures and substances

.
1.2 Empirical and molecular formula, Percent purity of a compound.

 

1.3 Mole and quantative calculations based on mole concept. Atomic mass unit in amu and gram. Average atomic masses and relative atomic masses. Avogadro’s number and molar mass.

 

1.4 Electrons, protons and neutrons Coulomb’s law, Ionization energies Photo electron spectroscopy (PES). Calculations of the ionization energy using photoelectric effect. Use of PES to determine. the electriconic configurations of atoms in multi electrons system.

 

1.5 Elctronic configurations, quantum numbers.Hund’s Rule, Aufbau principle, Heisenberg’s uncertainity principle,Pauli's exclusion principle shells, subshells, inner core electrons, valence electrons, Orbitals.


1.6 Periodicity and periodic table.  Predicting electronic configurations from the periodic table.Periodic trends for first Ionization Energy, atomic and ionic radii electronegativity and ionic charges. Similarity of chemical properties of the elements of the same group.Molecular designing based on periodic trends.


1.7 Different Atomic models and its refinement based on the Ionization energies values.

1.8 Mass spectroscopy, Isotopes and average atomic masses.


1.9 Electromagnetic waves or light Planck’s equation, photon, relation between energy of photon, wavelength frequency and wave number.


1.10 Importance of different spectral regions to determine. the type of bonds and to probe electronic structure.


1.11 Beer – Lambert’s law to determine. the concentrations of the solution.


1.12 Law of conservation of mass or matter during a chemical or physical process. Concept of balancing the reaction.


1.13 Types of the Chemical reactions. Gravimetric analysis of a sample from precipitation reaction. Calculations based on volumetric analysis of a sample using titration.

1.14 Identification of metallic and nonmetallic elements and substances . Acidic and basic properties from the Chemical formula.



Big Idea 2 : Solids , Liquids and Gases

 

2.1 Explanation of the states of matter on the basis of Inter-molecular forces of attraction,kinetic energy and temperature. Viscosity, surface tension and change in heat for mixing for liquids. Crystalline and amorphous forms of solids.Heating and cooling curves with phase changes.


2.2 Ideal gas laws based on relation between P, V ,n and T, Kinetic molecular theory,Maxwell – Boltzmann distribution curve.


2.3 Real gases deviation from the ideal behavior based on intermolecular interactions.


2.4 Solutions ,Homogenous and Heterogeneous solutions, colloids, seperation techniques for the components of the solutions based on their chemical and physical properties,dissolution process, molarity, dilution chemistry.


2.5 Types of intermolecular forces. London Dispersion forces,polar and non polar molecules, Polar forces and hydrogen bonding,Dipole moment.


2.6 Intermolecular forces and properties of the substance. Boiling point surface tension, capillary action, vapor pressure, viscosity, solubility and deviation from the ideal behavior. Biological reactions affected by the nature and the type of the intermolecular forces like interaction of enzyme with the substrate, Hydrophobic and Hydrophilic regions in proteins.


2.7 Chemical bonding, valence electrons, inert gas configurations, covalent bonding, Ionic bonding, polar covalent bond. Ionic and covalent character in a compound, Bond energies, metallic bonding and delocalization of electrons.


2.8 Lewis diagram, use of VSEPR model to determine molecular geometry,shape, bond angles, dipole moment, bond lengths and bond energies. Limitation of Lewis diagrams. Hybridization sp, sp2 and sp3.Use of hybridization in predicting the molecular geometry and bond angles.


2.9 Molecular orbital theory and understanding of sigma and pi bonds.


2.10 Types of solids, Ionic solids, covalent solids, metallic solids ,and molecular solids.


Big Idea 3 : Chemical Changes

 

3.1 Types of Chemical reactions and balancing of reactions.


3.2 Writing of the molecular equations, Ionic equations and net ionic equations on the basis of solubility rules.


3.3 Quantitative information from the balanced reaction using stoichiometric calculations, mole concept, Limiting reactant, % yield, determination of molar mass of gases, titrations to know the concentrations in the solutions.


3.4 Acid-Base Reactions in aqueous medium ,Bronsted Acid Base theory, Conjugate acid-base pairs ,strength of Acids and bases and relative strengths of conjugate acid-base pairs.


3.5 Reduction -Oxidation reactions, assigning oxidation numbers, Identification of a reaction as redox reaction and its balancing.


3.6 Identification of a Chemical change on the production of heat, formation of a gas, formation of a precipitate or a color change. Laboratory exercises based on chemical changes.


3.7 Energy changes during a chemical reactions. Exothermic and endothermic reactions and graphical depiction of the processes as energy diagram.


3.8 Chemical energy and electrical energy. Galvanic cell and voltaic cell, representation of cells, Calculations of standard cell potential ,Relation between K, ? Go, Eocell and spontaneity of the reactions, Equilibrium and Eocell, concentration cells ,Qualitative reasoning about the effects of the concentrations on the cell potential. Faraday’s law which is used to determine the stoichiometry of the redox reactions like to calculate the amount of current, time and mass of the metal deposited.


 


Big Ideas 4 : Chemical Kinetics

 

4.1 Rate of the reaction, factors responsible for the change in the rate of a reaction, rate constant.


4.2 Rate law, order of a reaction, integrated rate laws. To determine the order of the reaction from the graph of concentration vs time, initial rates of the reactions.


4.3 Rate constant, calculations of the rate constant, units of the rate constant, temperature dependence of the rate constant, Half life for the first order reaction.


4.4 Collision theory and order of the reaction, molecularity of the reaction. Effective collisions and Activation energy barrier ,Arrhenius equation.


4.5 Mechanism of the reactions, reaction intermediates and rate determining step.


4.6 Effect of the catalyst on the rate of the reaction, acid-base catalysis, surface catalysis and enzyme catalysis.

 

Big Idea 5 : The laws of thermodynamics

 

5.1 Heat, temperature, kinetic energy, Law of conservation of energy, Relation between work energy and heat.


5.2 Enthalpy, endothermic and exothermic process, specific heat capacity, phase transitions, molar enthalpy of vaporization, molar enthalpy of fusion. Calorimetry and Calculations based on the Calorimetry experiment.


5.3 Bond Enthalpies, Potential energy relation with the atoms or ions and the electrostatic interactions between them. Calculation of the enthalpy of the reactions from bond enthalpies.


5.4 Hess’s law, Enthalpies of formation, application of enthalpies of formation table on the extraction of metal from their oxides.


5.5 Potential energy is associated with the interaction of molecules, as molecules draw near each other, they experience an attractive force. Interactions involved in physical and chemical changes, Non covalent and intermolecular interactions in biological and polymer system.


5.6 Spontaneity of a chemical reaction or physical change on the basis of gibb’s free energy change and entropy.

5.7 Entropy as a measure of dispersal of matter and energy, spontaneous and non-spontaneous reactions relation between entropy, enthalpy and Gibb’s free energy change. Use of electricity and light energy for driving a process which are not thermodynamically favored.


5.8 Kinetically controlled or thermodynamically controlled processes. Activation Energy factor for determining if it is kinetically or thermodynamically controlled.


Big Idea 6 : Equilibrium

 

6.1 Chemical equilibrium, dynamic equilibrium, rate of the forward and reverse reaction, Extent of the reaction from K .Comparison of Q (reaction quotient) with K to know the direction of the reaction.


6.2 Calculations of the equilibrium, concentrations from the ICE Table. Graphical representation of the equilibrium state for simple chemical reactions.


6.3 Effect of change in pressure, temperature volume, concentrations and catalyst on the Chemical equilibrium ,Le chatelier’s principle.


6.4 Acids-Bases ,chemical equilibrium pH, pOH, pKa, pKb, Kw and pKw, Calculations of pH of weak acids and bases using ICE Table,Calculations based on titration, Polyprotic acids and use of titrations curves to evaluate the number of removable protons.


6.5 Concept of buffer, mechanism of the buffer, buffer capacity ,calculations of the pH of the buffer. Preparation of buffer solution of desired pH (including polyprotic acids), Acid-Base indicators and protonation of proteins, pH required for acid catalyzed reaction in organic reactions.


6.6 Solubility of a substance, Ksp, the solubility product. Effect of the pH, common ion and temperature on the solubility of the substance.


6.7 The relation between the Chemical equilibrium constant and Gibb’s free energy change.
K = e -? G/RT Quantitative or Qualitative estimation of the K of the reaction. Exergonic or Endergonic processes.

Beyond the scope of the AP Exam and you will NOT be tested in these topics :

(1)    Exceptions to the Aufbau Principle
(2)    Assignment of quantum numbers to the electron
(3)    Phase diagram
(4)    Calculations of molality, percent by mass and percent by volume.
(5)    Colligative properties
(6)    Weaker hydrogen bonding Hydrogen bonding due to high electronegative elements N, O, F will be tested.
(7)    Crystal shapes or structures
(8)    Use of Formal change to explain why certain molecules do not obey the octet rule.
(9)    Limitations of Lewis dot model
(10)  Molecules orbital diagrams, and filling of orbital diagrams.
(11)  Varieties of crystal lattices for ionic compounds.
(12)  Lewis- acid- Base concepts
(13)  Language of reducing agent and oxidizing agent.
(14)  Labeling electrodes as positive or negative.
(15)  Nernst Equation Calculations. Qualitative reasoning based on the Nernst Equation is the part of the exam.
(16)  Calculations based on Arrhenius equation. Conceptual aspects and interpretation of graphs is the part of the course.
(17)  Calculations of the concentration of each species present in the titration curve for polyprotic acids.
(18)  Calculations of the change in pH due to addition of an acid or a base to a buffer.
(19)  The derivation of the Henderson – Hasselbalch equation.
(20)  Memorization of solubility rules’ other than that all salts of first group ions, ammonium and nitrates are soluble in water.


Study Material for AP Chemistry
1. Chemical Foundations  
1.1 Scientific Methods Open .pdf presentation
1.2 Units of Measurement Open .pdf presentation
1.3 Uncertainty in Measurement Open .pdf presentation
1.4 Significant Figures and Calculations Open .pdf presentation
1.5 Dimensional Analysis Open .pdf presentation


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