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

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? Answer: To find atoms of carbon, we take the number of hydrogen atoms and multiply the number by 19/28 (ratio of carbon to hydrogen atoms), thus cancelling the number of hydrogen atoms and getting carbon atoms. To find, the number of molecules we use the ration of 1/28, where 1 molecules of C19H28O2 has 28 H atoms. To find the moles of testosterone, we have to use Avogadro's number 6.022 molecules/mol t

Which Compound Is An Electrolyte?

Which compound is an electrolyte? (1) CH3CHO (2) CH3OCH3 (3) CH3COOH (4) CH3CH2CH3 Answer: Choice 3 CH3COOH is the correct answer choice Explanation: 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 of bases is on the Regent Reference table) All the compounds listed in the answer choices are organic because they have a carbon. If we look at their function groups, we can determine that CH3CHO is an aldehyde (CHO), CH3OCH3 is an ether, CH3COOH is an organic acid an

How To Ace Your Organic Chemistry Class?

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 check with the answers to make sure you did it correctly. 2. Go over classwork and HW problems. Practice is of outmost importance in organic chemistry. Practice problems from classwork, HW, and end of chapter every day. Practice will make it easier for you to remember reactions a

How To Name Acids

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 H2SO4, HNO3 Naming an oxoacid: The name of an oxoacid depends on the ending of the polyatomic ion. Here is the chart to help you with naming: Polyatomic Ion name Acid Name per_____________ate = per_____ic ______ate = _____ic ______i

Altitudes in right, acute, obtuse and equilateral triangles.

Definitions: 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 orthocenter outside of the triangle. Equilateral Triangle - is a triangle where all of the sides are equal to one another. An equilateral triangle also has equal angles, 60 degrees each. In an equilateral triangle the orthocenter lies inside the triangle and on the perpendicular bisect

The processes of diffusion and active transport are both used to

The processes of diffusion and active transport are both used to break down molecules to release energy move molecules into or out of cells of the body bring molecules into cells when they are more concentrated outside of the cell move molecules against a concentration gradient, using ATP molecules Answer: Choice 2 is the correct answer Explanation: Diffusion is the passive movement of particles from the area of higher concentration to the area of lower concentration. This change in concentration is called concentration gradient. Diffusion is a passive process and does not require energy. Active transport is the movement of particles from lower concentration to higher concentration. Therefor

How to convert moles into mass (grams)?

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 number of moles by the molar mass. Let's look at the units: moles * grams/mols = moles will cancel giving us grams only. Let's now look at an example Example: What is the mass, in grams, of 1.223 mol of iron(III) sulfate? Answer: iron(III) sulfate has the formula Fe2(SO3)3 ( when

When Do Carbocation Rearrangements Happen?

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 often we have a secondary carbocation in our intermediate that is next to either a tertiary or quaternary carbon. How do I know what to move during a carbocation rearrangement? Scenario 1 If you have a secondary carbocation in our intermediate that is next to either a tertiar

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

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 disordered. Between solid, liquid, and gas, solid is the lease disordered phase and gas is the most disordered phases. Now, let's look at the answer choices. The first choice is g to l, or gas to liquid. This should result in a decreases of entropy since liquid is less disordered than gas. T

The movement of the calcium ions into certain cells is most likely due to

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 produces mostly females. Scientists recently discovered a thermosensor protein, TRPV4, that is associated with this process in American alligators. TRPV4 is activated by temperatures near the mid-30s, and increases the movement of calcium ions into certain cells involved with

If g(x)= 􏰁-4x^2-3x+2, determine g(􏰁-2)?

If g(x)= 􏰁-4x^2-3x+2, determine g(􏰁-2)? Algebra 1, August 2019 Regent exam Answer and Explanation: We have a function g of x, where x can be any number or variable. To calculate g(􏰁-2), all we need to do is to plug in -2 in the equation everywhere we see x. Therefore, this equation becomes g(-2)= -􏰁4(-2)^2-3(-2)+2 = -4(4)+6+2= -8 The answer for this problem is -8 Hint: Every time we have a function such as g(x) and are asked to calculate g of something, we just plug that something instead of x. Let's take a look at a couple of other examples. Lets say we have f(x) = 3x-5 Let's now calculate f(3), f(2a) and f(3b-4) Again, we need to keep in mind wherever we see x, just plug in the new val

How to identify an ionic vs covalent compound?

There is a simple and easy way to identify ionic versus compounds. Ionic compounds can be of three types: 1. Metal + Nonmetal To figure out whether an element is a metal or a nonmetal, look at the periodic table. Elements on the right of the staircase on the periodic table are metals. Elements to the left of the staircase on the periodic table are nonmetals. Hydrogen is a nonmetal even though it is located on the right side. Examples: KCl, BaS 2. Metal + Polyatomic ion Polyatomic ions are ions that are made of multiple atoms. Students taking chemistry regent exam can find a list of polyatomic ions in Table E on the reference table. Examples: KNO3, Mg(OH)2 3. Polyatomic ion + Polyatomic ion

Which group of organisms in an ecosystem fills the niche of recycling organic matter back to the env

Which group of organisms in an ecosystem fills the niche of recycling organic matter back to the environment? August 2019 Biologu Regent Exams (1) carnivores (2) decomposers (3) producers (4) predators Answer and Explanation: In order for us to determine the correct answer, we need to know the definitions for each one of the answer choices. Carnivores are organisms that eat other animals. Examples of carnivores are lions and lady bugs. Decomposers are organisms that break other organisms down and return nutrients back to the soil. Therefore, they also recycle organic matter back to the environment, making choice 2 the correct answer choice. Examples of decomposers are bacteria and fungi. Let

The hydrogen ion concentration of a solution prepared by diluting 50. mL of 0.10 M HNO3(aq) with wat

SAT Chemistry practice from College Board The hydrogen ion concentration of a solution prepared by diluting 50. mL of 0.10 M HNO3(aq) with water to 500. mL of solution is (A) 0.0010 M (B) 0.0050 M (C) 0.010 M (D) 0.050 M (E) 1.0 M Answer and Explanation: One of the key words in this question is diluting. A solution gets diluted when more water is added and thus the concentration decreases. The formula for dilution is M1V1=M2V2 where M stands for molarity and V stands for volume. Volume can have any units as long as both sides are consistent. We should also realize that HNO3 is a strong acid. Strong acids dissociate completely, and therefore the molarity of the strong acid equals the hydrogen

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For a chemical system at equilibrium, the concentrations of both the reactants and the products must

For a chemical system at equilibrium, the concentrations of both the reactants and the products must (1) decrease (2) increase (3) be constant (4) be equal Answer and Explanation: Some reactions go to completion, where the reactants react completely to form products. Other reactions, however, do not go to completion but rather reach equilibrium where as the reactants form products, product react to form reactants. At equilibrium, the rates of the forward and reverse reactions are equal. The concentration of both the reactants and the products are constant. Therefore, choice 3 is the correct answer choice. At Transformation Tutoring, we love chemistry and love teaching. We are so proud of ou