September 30, 2019

A sample of the male sex hormone testosterone,C19H28O2, contains 3.88 * 10^21 hydrogen atoms.

(a) How many atoms of carbon does it contain?

(b) How many molecules of testosterone does it contain?

(c) How many moles of testosterone does it contain?

(d) What is the mass of this sample in grams?


To find atoms of carbon, we take the number of hydrogen atoms and multiply the number by 19/28 (ratio of carbon to hydrogen...

September 27, 2019

Which compound is an electrolyte?

(1) CH3CHO

(2) CH3OCH3


(4) CH3CH2CH3

Answer: Choice 3 CH3COOH is the correct answer choice


Electrolytes are compounds that can conduct electricity.

Electrolytes are: 

Ionic compounds melted or dissolved in water (ionic means metal +nonmetal, metal +polyatomic ion, or two polyatomic ions together).

Acids (The list of acids is on the Regent Reference table) 

Bases (The list...

September 26, 2019

Organic chemistry is notorious for being one of the hardest subjects in college. Don't panic though. Here is a list of how to best study and ace your organic chemistry class.

1. Read the chapter, paying most attention to the in chapter problems. Some students even skip reading the chapter since problems practicing is most important for organic chemistry. You can try to do the in-chapter problems on your own and then chec...

September 25, 2019

How To Name Acids 

An acid is a substance that releases H+ ions (hydrogen ions) when it is dissolved in water.

Acids can be divided into 2 categories: binary acids and oxyacids.

Binary Acid - consists of H + nonmetal

Examples of binary acids are HCl, H2S, HBr

Naming a binary acid - HYDRO _____ IC ACID

HCl - hydrochloric acid

H2S - hydrosulfuric acid

Oxoacid - consists of H + Polyatomic ion containing O

Examples of oxoacids are H...

September 24, 2019


An altitude of a triangle is a line segment through the vertex and perpendicular to the base. 

All three altitudes intersect at the same point called orthocenter

Right Triangle - has a 90 degree angle, altitudes meet at the vertex of the right angle

Acute Triangle - has an angle less than 90 degrees, altitudes meet inside the triangle 

Obtuse Triangle - has an angle more than 90 degrees and has an orthoce...

September 24, 2019

The processes of diffusion and active transport are both used to

  1.  break down molecules to release energy

  2.   move molecules into or out of cells of the


  3.   bring molecules into cells when they are

    more concentrated outside of the cell

  4.   move molecules against a concentration

    gradient, using ATP molecules

Answer: Choice 2 is the correct answer

Explanation: Diffusion is the passive movement of pa...

September 23, 2019

How to convert moles into mass?

To convert moles into mass, we first need to find the molar mass of the compound given. This can be done by looking at the mass of each element in the periodic table and then multiplying each mass by the number of atoms of that element in the compound. Molar mass has the units grams/mol which allows to convert between moles and grams.

To go from moles to grams, we need to multiply the numbe...

September 18, 2019

When Can Carbocation Rearrangements Happen?

Carbocation Rearrangements can occur in reactions whose mechanism goes through carbocation (C+) intermediates. These reactions are SN1, E1 and the reaction of alkenes (c=c) with an acid.

How do I know if the carbocation rearrangement will happen during my mechanism?

If you have a carbocation and the neighboring carbon is more substituted, you need to do the rearrangement. Most of...

September 17, 2019

January 2019 Chemistry Regent

During which phase change does the entropy of a sample of H2O increase?

(1) H2O(g) → H2O(l)

(2) H2O(g) → H2O(s)

(3) H2O(l) → H2O(g)

(4) H2O(l) → H2O(s)

Answer and Explanation:

Entropy represents disorder in chemistry. Universe wants to be as disordered as possible and therefore increasing disorder, or entropy, is favorable. Now, lets lookout phases to figure out what is more d...

September 16, 2019

Living Environment Regent August 2019

Base your answers to questions 36 through 39 on the information and photograph below and on your knowledge of biology.

Scientists Investigate Sex Determination in Alligators

The sex of some reptiles, including the American alligator, is determined by the temperature at which the eggs are incubated. For example, incubating them at 33°C produces mostly males, while incubation at 30°C pro...

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