Whats the Boiling point of a Solution made by dissolving 31 g of NaCl of Water?

Consider the pka (3.75) of formic acid, h-cooh as a reference. with appropriate examples, show how inductive, dipole, and resona

Luden [163]

Formic acid is the simplest carboxylic acid with a structure of HCOOH and has a pka of 3.75. The pka refers to the acidity of the molecule, which in this example refers to the molecules ability to give up the proton of the O-H. A decrease in the pka value corresponds to an increase in acidity, or an increase in the ability to give up a proton. When an acid gives up a proton, the remaining anionic species (in this case HCOO-) is called the conjugate base, and an increase in the stability of the conjugate base corresponds to an increase in acidity.

The pka of a carboxylic can be affected greatly by the presence of various functional groups within its structure. An example of an inductive effect changing the pka can be shown with trichloroacetic acid, Cl3CCOOH. This molecule has a pka of 0.7. The decrease in pka relative to formic acid is due to the presence of the Cl3C- group, and more specifically the presence of the chlorine atoms. The electronegative chlorine atoms are able to withdraw the electron density away from the oxygen atoms and towards themselves, thus helping to stabilize the negative charge and stabilize the conjugate base. This results in an increase in acidity and decrease in pka.

The same Cl3CCOOH example can be used to explain how dipoles can effect the acidity of carboxylic acids. Compared to standard acetic acid, H3CCOOH with a pka of 4.76, trichloroacetic acid is much more acidic. The difference between these structures is the presence of C-Cl bonds in place of C-H bonds. A C-Cl bond is much more polar than a C-H bond, due the large electronegativity of the chlorine atom. This results in a carbon with a partial positive charge and a chlorine with a partial negative charge. In the conjugate base of the acid, where the molecule has a negative charge localized on the oxygen atoms, the dipole moment of the C-Cl bond is oriented such that the partial positive charge is on the carbon that is adjacent to the oxygen atoms containing the negative charge. Therefore, the electrostatic attraction between the positive end of the C-Cl dipole and the negative charge of the anionic oxygen helps to stabilize the entire species. This level of stabilization is not present in acetic acid where there are C-H bonds instead of C-Cl bonds since the C-H bonds do not have a large dipole moment.

To understand how resonance can affect the pka of a species, we can simply compare the pka of a simple alcohol such as methanol, CH3OH, and formic acid, HCOOH. The pka of methanol is 16, suggesting that is is a very weak acid. Once methanol gives up that proton to become the conjugate base CH3O-, the charge cannot be stabilized in any way and is simply localized on the oxygen atom. However, with a carboxylic acid, the conjugate base, HCOO-, can stabilize the negative charge. The lone pair electrons containing the charge on the oxygen atom are able to migrate to the other oxygen atom of the carboxylic acid. The negative charge can now be shared between the two electronegative oxygen atoms, thus stabilizing the charge and decreasing the pka.

3 0

3 years ago

Use the periodic table to select which type of bond is present and which of the listed properties is most

Kazeer [188]

Answer:

A= Metallic

B= Conducts electricity as a solid

C= Covalent

D=Does not conduct electricity

Explanation:

3 0

3 years ago

Zinc has a specific heat capacity of 0.390 J/goC. What is its molar heat capacity? Enter your answer numerically to three signif

ch4aika [34]

Answer:

The answer to your questions is Cm = 25.5 J/mol°C

Explanation:

Data

Heat capacity = 0.390 J/g°C

Molar heat capacity = ?

Process

1.- Look for the atomic number of Zinc

Z = 65.4 g/mol

2.- Convert heat capacity to molar heat capacity

(0.390 J/g°C)(65.4 g/mol)

- Simplify and result

Cm = 25.5 J/mol°C

3 0

3 years ago

Express the following in regular notation:<br> 3.4 x 10-1

sweet-ann [11.9K]

Answer:

hen working with very large or very small numbers, scientists, mathematicians, and engineers often use scientific notation to express those quantities. Scientific notation uses exponential notation. The following are examples of scientific notation.

Light year: number of miles light travels in one year, about 5,880,000,000,000

Scientific notation is 5.88 x 1012 miles.

hydrogen atom: has a diameter of about 0.00000005 mm

Scientific notation is 5 x 10-8 mm

Computation with very large numbers is made easier with scientific notation.

Learning to Use Scientific Notation

When a number is written in scientific notation, the exponent tells you if the term is a large or a small number. A positive exponent indicates a large number and a negative exponent indicates a small number that is between 0 and 1.

Since it’s so useful, let’s look more closely at the details of scientific notation format.

Scientific Notation

A positive number is written in scientific notation if it is written as a x 10n where the coefficient a has a value such that 1 ≤ a < 10 and n is an integer.

Look at the numbers below. Which of the numbers is written in scientific notation?

Number

Scientific Notation?

Explanation

1.85 x 10-2

yes

1 ≤1.85 < 10

-2 is an integer

no

is not an integer

0.82 x 1014

no

0.82 is not ≥ 1

10 x 103

no

10 is not < 10

Which number below is written in scientific notation?

A) 4.25 x 100.08

B) 0.425 x 107

C) 42.5 x 105

D) 4.25 x 106

Show/Hide Answer

Writing Decimal Notation in Scientific Notation

Now let’s compare some numbers expressed in both scientific notation and standard decimal notation in order to understand how to convert from one form to the other. Take a look at the tables below. Pay close attention to the exponent in the scientific notation and the position of the decimal point in the decimal notation.

Large Numbers

Small Numbers

Decimal Notation

Scientific Notation

Decimal Notation

Scientific Notation

500.0

5 x 102

0.05

5 x 10-2

80,000.0

8 x 104

0.0008

8 x 10-4

43,000,000.0

4.3 x 107

0.00000043

4.3 x 10-7

62,500,000,000.0

6.25 x 1010

0.000000000625

6.25 x 10-10

To write a large number in scientific notation, move the decimal point to the left to obtain a number between 1 and 10. Since moving the decimal point changes the value, you have to multiply the decimal by a power of 10 so that the expression has the same value.

Let’s look at an example.

180,000. = 18,000.0 x 101

1,800.00 x 102

180.000 x 103

18.0000 x 104

1.80000 x 105

180,000 = 1.8 x 105

Notice that the decimal point was moved 5 places to the left, and the exponent is 5.

The world population is estimated to be about 6,800,000,000 people. Which answer expresses this number in scientific notation?

A) 7 x 109

B) 0.68 x 1010

C) 6.8 x 109

D) 68 x 108

Show/Hide Answer

Advanced Question

Represent 1.00357 x 10-6 in decimal form.

A) 1.00357000000

B) 0.000100357

C) 0.000001357

D) 0.00000100357

Show/Hide Answer

To write a small number (between 0 and 1) in scientific notation, you move the decimal to the right and the exponent will have to be negative.

0.00004 = 00.0004 x 10-1

000.004 x 10-2

0000.04 x 10-3

00000.4 x 10-4

000004. x 10-5

0.00004 = 4 x 10-5

0.82 x 10-6

3 0

3 years ago

Read 2 more answers

Position (m)

Alex777 [14]

Option C. The object is returning to the start at a constant speed.

<h3>Data points of the Position vs Time graph</h3>

The following data points will be used to determine the motion of the object.

<u>Position Time</u>

12 4

10 6

2 8

0 10

From the data above, the position of the object is decreasing towards zero or start point.

Thus, the object is returning to the start at a constant speed.

Learn more about position here: brainly.com/question/2364404

#SPJ1

8 0

2 years ago