????how many students failed this science class???

Which element has the element configuration 1s2 2s2 2p4

expeople1 [14]

Answer:

O(Oxygen)

Explanation:

2+2+4=8

And the eighth element of the periodic table is Oxygen

3 0

3 years ago

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

Which law represents a balanced chemical equation?

Montano1993 [528]

Answer:

All chemical equations goes to the law of conservation of mass which says that matter can not be destroyed nor created which means there has to be an equal amount of atoms of each element on both sides of the equation. I hope that helps, I'm learning this as well.

8 0

2 years ago

Over a long period of time, an igneous rock changes into a sedimentary rock. Which of these actions must have affected the igneo

Alla [95]

Answer: The actions that must have affected the igneous rock in order to form the sedimentary rock is that (It must have been broken down into sediments).

Explanation:

Rocks are solid structures that occurs naturally which is made up of different minerals. There are three main types of rocks, these includes:

--> METAMORPHIC ROCKS: These are the type of rocks which are formed by temperature and pressure changes inside the Earth.

--> SEDIMENTARY ROCKS: these rocks are usually formed from pre-existing rocks through the process of weathering (breaking down) of rocks.

--> IGNEOUS ROCKS: these rocks are formed when molten magma cools beneath or above the earth surface.

The actions that must have affected the igneous rock in order to form the sedimentary rock is that the igneous rocks are broken down into smaller pieces by erosion and weathering processes. Sediments which are formed accumulates at the earth surface. Over a long period of time, these sediments builds successive layers on top of one another. The sediments near the base hardens to form sedimentary rocks. This justifies the statement as a correct option (It must have been broken down into sediments).

3 0

2 years ago

Identify which sets of quantum numbers are valid for an electron. Note that each set is ordered (n,l,ml,ms).

Fynjy0 [20]

Answer:

The answer to your question is:

Explanation:

Quantum numbers have the numbers

n = from 1 to 7

l = s = 0 p = 1 d = 2 f= 3

m = ± l

s = ±1/2

Group of answer choice.

A) 2, -1. 1, -1/2 The option is incorrect "l" could not be negative

B) 2, 1, 0 , 1/2 The option is posible

C) 3, 2, 1, -1 This option is incorrect "s" can not value -1

D) 4, 3, 2, 1/2 This option is correct

E) 4, 3, -4, 1/2 This option is incorrect "m2 can not value -4

F) 1, 1, 0, 1/2 This option is incorrect, the second number is not posible

G) 1, 1, 0, -1/2 This option is incorrect the second number could not be 1.

H) 3, 0, 0, 1/2 This option is incorrect "l" can not value 0

I) 0, 2, 0, 1/2 This option is incorrect, n can not value 0

J) 3, 2, 2, 1/2 This option is correct

K) 1, 2, 0, -1/2 This option is incorrect "l" can not value 2.

3 0

3 years ago