March 5, 2020

The number of different HNMR signals represent the number of different hydrogens. Here are the steps you need to do to correctly identify them.

1. Label all of the hydrogens in a molecule so you don't accidentally miss one, and don'd put a signal where the hydrogen in missing. In order to label the hydrogens, we need to remember that a carbon wants to have 4 bonds. Depending on how many bonds the carbon has, is how many...

February 25, 2020

Both molarity and molality are measures of concentration, or how much solute is dissolved in solvent. Let's first get acquainted with a couple of terms.

Solute -  what gets dissolved

Solvent - what the solute dissolves in

Solution - solute and solute together 

Now, we can write out formulas for our two terms.

Molarity(M) = moles of solute/ Liters of solution

Molality(m) = moles of solute/ kg of solvent

As evident from the form...

February 21, 2020

To arrange alkenes in order of stability, we need to know that the most substituted the double bond is, the more stable the alkene is. Alkenes can be divided into four categories: monosubstituted (double bond is directly attached to one carbon), disubstituted (double bond is attached to two carbons), trisubstituted (double bond is attached to three carbons), and tetrasubstituted (double bond is attached to four carbons)...

January 23, 2020

Which electron shell in an atom of calcium in the ground state has an electron with the greatest amount of energy?

(1) 1

(2) 2

(3) 3  

(4) 4

Answer: 4

Explanation: The further an electron is from the nucleus, the higher it's energy is. Therefore, electrons in the valence shell (outermost shell) have the highest amount of energy. If we look at the Reference Table: Periodic Table of Elements section, we can find calcium...

January 22, 2020

Lewis Dot structure is a representation of how electrons are arranged in a molecule.

To correctly draw lewis dot structures we need to follow the following six steps.

1. Calculate the total number of valence electrons

2. Connect atoms in a molecule using bonds

3. Subtract electrons used in bonds from the total electrons calculated in part 1

4. Use remaining electrons to make outer atoms happy (octet, 8 electrons) but rem...

January 21, 2020

The only two elements in alkenes and alkynes are

(1) carbon and nitrogen

(2) carbon and hydrogen

(3) oxygen and nitrogen

(4) oxygen and hydrogen

Answer: (2) carbon and hydrogen

Explanation:

If we look at the Chemistry Regent Reference table, we will see on Table Q, that alkenes and alkynes belong to the Homologous Series of Hydrocarbons. Hydrocarbons are organic molecules that contain carbon and hydrogen. Therefore, they mu...

December 27, 2019

Intermolecular forces are forces of attraction between molecules. These forces influence properties of substances such as boiling and melting points, phases at room temperature, viscosity and many more.

Intermolecular forces can be divided into 4 major categories:

1. ION-ION

This is the strongest intermolecular force. It is present in all ionic compounds. To recognize it, look at the formula and see if it has metal with a...

December 5, 2019

It's almost december and that means it's finals time! This can be very overwhelming and stressful. At Transformation Tutoring, we came up with tips on how to best prepare for your chemistry finals.

1. Make a to-do list. List items in terms of priority. Since time is limited, it is important to focus on the most important tasks that need to be done.  Make a big plan for the two upcoming weeks with major milestones (for ex...

December 3, 2019

Which of the following substrates would react most efficiently in a substitution reaction with sodium cyanide (NaCN)?

(A) 1-iodohexane
(B) 1-fluorohexane
(C) (R)-2-bromohexane
(D) chlorocyclohexane
(E) 1-bromo-1-methylcyclohexane

Answer: (A) 1-iodohexaneA

Solution:

We first must figure out which reaction does the question ask about. The question mentions substitution reaction, thus either SN1 or SN2. We are also given NaCN...

November 17, 2019

What is the chemical name of the compound NH4SCN?

(1) ammonium thiocyanate

(2) ammonium cyanide
(3) nitrogen hydrogen cyanide

(4) nitrogen hydrogen sulfate

Answer: (1) ammonium thiocyanate

Explanation: In order to name a compound, we must first figure out whether it is ionic or covalent. Ionic compounds can be divided into three categories: metal + nonmetal, meta+ polyatomic ion, polyatomic ion+ polyatomic ion, polyatomic io...

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