Monday, June 8, 2015

Diagram of Most Important Ideas for Chemistry AP, SAT, Regents, and Finals


A diagram of most important ideas for Chemistry SAT, AP, and Regents exams and how they are related
Map of important ideas in Chemistry for the SAT, AP, and Regents Exams
 I've sketched some of the most important topics for the SAT II Subject Test in Chemistry, AP Chemistry Exam, and New York Regents Chemistry exam. This is by no means an exhaustive concept map and includes only the most important relationships and how they stem from the basic interactions of protons, neutrons, and electrons. Each box can be further subdivided into its own map, especially for college general chemistry. In oversimplifying many ideas, there will invariably be some mistakes or some general rules that aren't true under all circumstances. For example, determining how polar a molecule is much more intricate than determining if the molecule is symmetrical and ionic/covalent but this will determine the vast majority of the simple cases in high school chemistry and is a great starting point.

     This can be broken up in many different ways but I wanted to include every major topic on these exams - Acids/Bases, Redox, Organic Chemistry, Ideal Gases, Kinetics/Thermodynamics, Phase Changes, and Solubility. It is important to understand how these complex phenomena stem from the basic concepts in order to ace the AP, SAT, and Regents Chemistry. I focused on how many of the chemical and physical properties of compounds we see around us everyday stem from electrons fitting into positions of lowest energy. One position of lowest energy that is common  is 8 valence electrons, which has many implications to the atom's attraction for other electrons, its shape, the ions they form, and other properties. Obviously, all three subatomic particles are intimately related. The number of electrons in a neutral atom is determined by the number of protons. The ratio of protons and neutrons must form a stable nucleus otherwise it will radioactively decay. However, since electrons want (excuse the personification) to form a stable configuration, they determine the periodic trends (such as electronegativity), how certain elements react, and the shape of the molecules that these reactions form. Polarity affects many physical properties such as boiling point and freezing point. All blue boxes and lines have to do with polar compounds such as acids/bases and compounds undergoing oxidation/reduction. Orange represents non-polar molecules such as organic hydrocarbons. Additionally, red is protons, green represents neutrons, gray signifies anything to do with electrons, and black denotes physical properties.

     Kinetics and equilibria can be used to determine reaction rates and results (or non-results) of reactions for all types of compounds. Nearly everything can be expressed using these phenomena. Intermolecular forces, pressure (from Ideal gases), and kinetics are just a couple of places from where a physics map can be expanded. It is equally hard to determine from where a map of topics in biology should ideally branch as all living things that we are aware of are based on organic chemistry. We use blood as a buffer to maintain out proper acid/base levels (pH). Bananas give off enough radiation that we measure exposure in "banana equivalent doses."It is best to look at chemistry, physics, and biology as one course because concepts from one discipline can often be explained by phenomena in the other two.

Please let me know if you would like me to expand upon this or make similar maps as I see them. For more details and regarding tutoring in NYC in Manhattan, Brooklyn, and Staten Island, contact me here.

Monday, May 18, 2015

How to Optimize True False questions on SAT II Chemistry Subject Test


In order to get a perfect 800 score on the SAT II Subject Test in Chemistry, the True-False section is the most unique and the most difficult for many students. In addition to the standard way to handle True-False questions, you must also bubble CE afterward if both statements are true and the second one would cause the first statement. A great strategy is to read both statements as one statement with a because between them in order to evaluate whether the combined statement is CE. Something can only be CE if both statement are true but they do not have to be CE. "True, True and not CE" is a possibility if there is no connection between the statements.

The True-False questions on the SAT II Subject Test in Chemistry start at number 101 on your answer sheet but are really about the 20th question in the test, right after the word bank problems. Don't be alarmed that start on number 101, you didn't miss any questions.There is no break between sections so you must keep track and optimize your time to tell if you need to speed up or have time to read questions more thoroughly.
Typically about fifteen True-False questions with two statements and evaluating the CE so this is the equivalent of between 30 and 45 questions. You need to be fairly quick on this section to answer the other 70 questions of so correct in the allotted hour (as outlined in the SAT and AP Chemistry exam format differences) so it would be great to finish these questions in about 10 minutes. It is not a bad idea to save these until the end although they are not very time consuming. You essentially have to get all 3 questions of each set correct in order to get credit for that question. There is no partial credit. If you get any part wrong, you lose a quarter of a point. Since probabilities on compound events are multiplicative, being slightly unsure about any one statement can dramatically increase the chance that you are incorrect in total.

Since you do not need to get everything correct on SAT II Subject Test in Chemistry test for an 800, you may want to skip some questions that you are completely unsure in order to optimize your score. You don't lose any points for skipping but lose a quarter of a point for an incorrect answer on the True False section, equivalent to each question on any other section. Since there is so little time for so many questions, the worst thing you can do is spend a lot of time on any one question and still get it wrong. Depending on the pool of students taking the test, you can get about two wrong or leave a couple more blank and still get an 800. Have a plan on deciding what types of questions you want to leave blank or skip until the end if you have time. Don't waste precious time deciding that during your test. Ideally, you want to be prepared and confidently execute your strategy on each type of problem as you see it.

The SAT Subject Test in Chemistry True False questions typically include definitions or properties that can be memorized or figured out based on understanding some common phrases and ideas, which overlap heavily with the AP Chemistry Exam and Regents Chemistry Exam. Important topics highly covered in the True False questions include properties of the nucleus and electrons, periodic trends, molecular geometry of common molecules and how that affects polarity, intermolecular forces, phase changes, and solubility rules. Formulae for organic molecules and spotting functional groups (some reactions as well) are important. Conservation of mass, energy, and charge is usually tested as well as other thermodynamics such as Gibb's Free Energy and its relationship to entropy, enthalpy, and the formation of bonds. Names and properties of common compounds as well as real world laboratory knowledge is included - paying thorough attention in lab (and class of course!) throughout the year will greatly help. No ice charts or complex equilibria and there is very little stoichiometry or anything else math related )like ideal gas laws or energy through a temperature or phase change). If they do ask something math-based on these, they are usually much simpler than the rest of the test and should be a quick mental calculation.

There is typically little math on these types of questions so some statements can be slightly ambiguous. Invariably, there will be at least a couple of questions in which you are unsure. If you can evaluate at least one of the statements, you can increase your percentage to get it correct and minimize your chance to get it wrong by checking if there is a relationship between the two.

You may be tempted to conclude that each has a 20% chance to be the correct answer, but each probability is not equal. Here is how I calculated the probability of any one choice. You do not need to understand this in order to apply the principles that can be concluded from it so feel free to skip this part until the bullets below. Assume each statement is an independent event. The first statement has a 1 out of 2 (50% chance) to be True and 50% chance to be False. If the first statement was False, the second statement has a 50% chance to be True and a 50% chance to be False. Since the probability of independent events is multiplicative, there is a 25% chance ( 50% chance * 50% chance) to be "False, True" and a 25% chance to be "False, False." Similarly, there's a 25% chance to be "True, False" and a 25% chance that the first two statements are true. If the first statement is True and the second statement is True, there's a 50% chance that it can be CE and a 50% chance of not CE (just True, True). Therefore, True, True, CE has a 12.5% (50% of 25% from "True, True"). This is not necessarily the breakdown of the correct answers on the test, but it will allow us to make some better decisions when faced with questions about which we are unsure.

There are 5 different choices for each questions:
  • True, True, CE = Both statement are true and the second one causes the first one = 12.5% probability
  • True, True = Both statements are true but there is no relationships between them = 12.5% probability
  • True, False = The first statement is true and the second statement is false = 25% probability
  • False, True = The first statement is false and the second statement is true = 25% probability
  • False, False = Both statements are false = 25% probability

As you can see from the list above, if the first statement is True, the second statement can be True or False (equally as likely), but if True can be CE or not CE (equally as likely as each other). Therefore, the probability of "True, True, CE" + probability of  "True, True" = the probability of each of the other choices individually. We can use these probabilities to give us an extra edge when we are not sure.

A great strategy to optimize your score is when you are unsure is to look toward the second choice:
  1. When in doubt, choose "False, True" if you know the second statement is True and there is no relationship.
  2. Even if you are completely unsure about the validity of the second statement but know the second statement would prove the first one true if the second were true, the correct answer is likely "True, True, CE."
False, True example
If the second statement is True and you know there is no relationship, the second statement is likely False and the correct choice is likely "False, True".
Catalysts get denatured in a reaction.      A catalyst can reduce the activation energy of a reaction.
The second statement is definitely true as that is an important common idea but there is no relationship between reducing the activation energy and getting denatured so the correct answers is False, True.

True, True, CE example where the definitions are unknown
If the second statement is True and would prove the first statement, then the best answer is likely "True, True, CE."
First statement: A dogalyst's area can be calculated by squaring its radius and multiplying by pi.
Second statement: A dogalyst is a circle.
Let's assume that a dogalyst exists for the time being (it might but I tried to make up something that's nonsensical). If you came across this problem and had no clue about the first statement, look toward the second statement. Once again, the second statement is ambiguous but does reveal a relationship between the two statements. If the the second statement is true, it would prove the first statement. Circles can be calculated through the formula pi r^2. Therefore, the best answer on a test in a situation like this would be "True, True, CE."

True True, not CE example
A catalyst can speed up reaction           Catalysts are reusable
These actually exist and are common ideas that you should know for the SAT Chemistry. Catalysts do speed up reactions and they are reusable; however, they don't have much of a relationship between each other under most high school level conditions. Therefore, True, True and NOT CE is the best choice. You do not have to fill in NOT CE, just leave the CE bubble unfilled.

Pay attention to absolute words (I don't mean Kelvin temperature but those are important as well) like always and never. These are almost always false as there are usually exceptions in various situations. When in doubt, go with False.

Pay attention to qualifier words like sometimes, likely, often, can, or may. These may make many but not all statements true. Read everything as thoroughly as possible.

If you cannot apply any of the tips above and if you have never heard of it before, go with False unless you can show a relationship like above. If you have taken a high school chemistry class, have taken practice exams, and have a tutor, there is nothing that should be surprising.

Please share any other tips or tactics for acing the SAT II Subject Test in Chemistry in the comments below.

 www.masterofchemistry.com/contact-me

Tuesday, April 28, 2015

Difference between AP Chemistry Exam and SAT Subject Test in Chemistry

The Chemistry Advanced Placement Exam and SAT Subject Test in Chemistry require similar skill sets but slightly different preparation. For both, a tutor can give your high school student the edge on a competitive field. SAT Chemistry is a great exam to have on your college application as most competitive schools require three SAT II Subject Tests. If they do not require them, strong scores give an important advantage over the competition. AP Chemistry is typically taken to earn college credit to place out of expensive college classes, although they can still be used to help your college application. You do not need to formally take an AP Chemistry course for the AP but it is recommended.
 
Format is biggest difference. The SAT 2 Chemistry is only about an hour for 85 questions whereas the AP is three hours and fifteen minutes for 67 questions. There are many more questions on the AP including many short answers in which you can receive partial credit, whereas the SAT Chemistry exam consists of all multiple choice. The SAT Chemistry tends to be a little more fact based whereas the AP Chemistry is a little more application based.

There is no calculator allowed on SAT Chemistry but on AP Chemistry you can use a calculator on the free response questions, not on the multiple choice. The math for the SAT and AP Chemistry exam is easily doable without a calculator with some mental math "tricks." Nothing is truly a trick if you understand how it works.

For the SAT Chemistry, you are only given a Periodic Table but for AP Chemistry you are given an extensive equation sheet as well. You will only need to memorize some of these formulae for the SAT Chemistry as they ask slightly quicker, less in depth questions.

When taking the SAT Subject test in Chemistry, you may take other SAT Subject Tests as well. It may be a good idea to take this test before any other SAT Subject Tests as it can be extremely difficult. For the AP Chemistry, you can only take that test for the day. It may also be a good idea to take the SAT Chemistry exam in June after the AP Chemistry instead of taking them both close together. You'll find that you will master some material while taking the AP that you will need for the SAT. Tests are always learning experiences no matter the preparation. Even after years of doing something, there are still connections that you make.




Advanced Placement Chemistry
SAT II Subject Test in Chemistry
Length
3 hours and 15 minutes
1 hour
Questions
67 (60 multiple choice and 7 short answer)
85
(all multiple choice)
Given
Useful formula sheet and Periodic Table
Periodic Table
Can I use a Calculator?
Not for multiple choice, Yes on free response

Not at all
Offered
May
May, June, October, November, December
When to register?
March 2
Typically about 1 month prior
Cost as of April 2015
$91 but $28 less if require financial assistance
About $42 depending on your variables and how many SAT Subject tests you take that day
Calendar and Registration


The SAT Subject Test in Chemistry has 3 types of questions - word bank characteristics, True/False, and multiple choice. The word bank problems require you to match a choice with the corresponding idea from their choices for consecutive problems. These groups can include laboratory equipment, famous experiments, scientists, colors of elements, properties of chemicals, or even more broad ideas from anything in high school chemistry. Just because one idea is used does exclude it from being the answer to another question. The True/False questions are unique in that you also have to write C/E (Cause/Effect) if the first part would be proved by the second part. Something can only be C/E if both statements are True but just because both statements are true does not mean it is C/E. When unsure, a good trick on these is to ask whether the second statement would prove the first statement or say because between them. If so, True/True, C/E is likely the correct choice. For the multiple choice, you can expect the dreaded "I, II, III" questions where they ask if it's I, II, II, I and II, II and III, all of the above, or some combination in the multiple choice section. These are typically difficult, consume a lot of time, and should be skipped until the end.

The Advanced Placement only has two sections but there is a small break in between. The multiple choice is 60 questions in 90 minutes and are similar to the SAT subject test although some types of questions are more common than others. The seven short answer questions take 105 minutes (15 minutes have been added to this section in 2015) and allow use of a calculator. Design of an experiment is included. Some questions require a correct answer to the previous question so make sure you read the whole set questions prior to answering the first.

Both tests require extensive understanding of chemical and physical phenomenon. including stoichiometry, bonding, intermolecular forces and their affect on colligative properties, kinetics, equilibria, oxidation/reduction, acids and bases, thermodynamics as well as test taking abilities. Practicing how to thoroughly read a question properly, learning which questions to skip, and how to solve some seemingly complex questions simply can make a daunting set of exams very manageable. These skills will remain useful for SAT and AP Physics which most students in New York take the year after AP and SAT Chemistry. Physics and Chemistry share many overlaps and can be thought of as one subject.


Formula Sheet and Calculator Policy for the AP:  https://apstudent.collegeboard.org/apcourse/ap-calculus-ab/calculator-policy

www.masterofchemistry.com/contact-me -Inquire for tutoring in SAT and AP Chemistry Exams in Manhattan, Staten Island, or Brooklyn

www.masterofchemistry.com  
 
Sources: 
http://apcentral.collegeboard.com/apc/public/courses/teachers_corner/2119.html

https://sat.collegeboard.org/practice/sat-subject-test-preparation/chemistry?chem

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