What is the density of 19.2 g of oak that has a volume of 25.7 cm3?

spayn [35]

Gravity is the force that draws water back to the earth in the forms of rain, sleet and, snow.

7 0

3 years ago

The theory of plate tectonics describes the movement of continental plates across the Earth's surface as if they were riding on

emmainna [20.7K]

Answer:

B and E

Explanation:

These two options support the theory of plate tectonics.

3 0

3 years ago

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Which of the following statements is TRUE? Which of the following statements is TRUE? Two electrons in the same orbital can have

Monica [59]

An orbital that penetrates into the region occupied by core electrons is less shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy.

Explanation:

The only true statement from the given options is that "an orbital that penetrates into the region occupied by core electrons is less shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy." Inner orbitals which are also known to contain core electrons feels the bulk of the nuclear pull on them compared to the outermost orbitals containing the valence electrons.

The nuclear pull is the effect of the nucleus pulling and attracting the electrons in orbitals.
This pull is stronger for inner orbitals and weak on the outer ones.
The outer orbitals are said to be well shielded from the pull of the nuclear charge.
Also, based on the quantum theory, electrons in the outer orbitals have higher energies because they occupy orbitals at having higher energy value.

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8 0

2 years ago

Why do you require an acid catalyst to make an ester? Why not just mix acid and alcohol? Describe an alternate method of making

djverab [1.8K]

Answer:Acid catalyst is needed to increase the electrophilicity of Carbonyl group of Carboxylic acid as alcohol is a weak nucleophile.

Alternatively esters can be synthesised by converting carboxylic acid into acyl chloride using thionyl chloride(SOCl_{2} and then further treating acyl chloride with alcohol.

Carboxylic acid and esters can be easily distinguished on the basis of IR as carboxylic acid would contain a broad intense peak in 2500-3200cm_{-1} corresponding to OH stretching frequency whereas esters would not contain any such broad intense peak.

Alcohol and esters can also be distinguished using IR as alcohols would contain a broad intense peak at around 3200-3600cm_{-1}

Explanation: For the synthesis of esters using alcohol and carboxylic acid we need to add a little amount of acid in the reaction . The acid used here increases the electrophilicity of carbonyl carbon and hence makes it easier for a weaker nucleophile like alcohol to attack the carbonyl carbon of acid.

The oxygen of the carbonyl group is protonated using the acidic proton which leads to the generation of positive charge on the oxygen. The positive charge generated is delocalised over the whole acid molecule and hence the electrophilicity of carbonyl group is increased. Kindly refer attachment for the structures.

If we simply mix the acid and alcohol then no appreciable reaction would take place between them and ester formation would not take place because the carboxylic acid in that case is not a good electrophile whereas alcohol is also not a very strong nucleophile which can attack the carbonyl group.

Alternatively we can use thionyl chloride or any other reagent which can convert the carboxylic acid into acyl chloride. Acyl chloride is very elctrophilic and alcohol can very easily attack the acyl chloride and esters could be synthesized.

The carboxylic acid and ester can very easily be distinguished on the basis of broad intense OH stretching frequency peak at around 2500-3200cm_{-1} . The broad intense OH stretching frequency peak is present in carboxylic acids as they contain OH groups and absent in case of esters .

Likewise esters and alcohols can also be distinguished on the basis IR spectra as alcohols will have broad intense spectra at around 3200-3600cm_{-1}corresponding to OH stretching frequency whereas esters will not have any such peak. Rather esters would be having a Carbonyl stretching frequency at around 1720-1760

4 0

2 years ago

The following combinations are not allowed. If n and ml are correct, change the l value to create an allowable combination:

motikmotik

The allowable combination for the atomic orbital is n=3, l=1, $m_{l}$ =-1.

<h3>What are the three quantum numbers of an atomic orbital?</h3>

Three quantum numbers specify an atomic orbital:

- The principal quantum number, n, which is a positive integer, describes the relative size of the orbital and its distance from the nucleus.

- l is the angular momentum quantum number that is related to the shape of the orbital; l is an integer from 0 to n-1 (so n limits l ),

- $\boldsymbol{m}_{l}$ is the magnetic quantum number that prescribes the three-dimensional shape of the orbital around the nucleus; $m_{l}$ values are integers from -l to =l(l limits ml)

For n = 3, l can have three values: 0, 1, and 2. Since $m_{l}$ values are integers from -l to 0 to +l, for l = 0 the value of $m_{l}$ cannot be -1 (l = 0 has $m_{l}$ = 0).

There are two l values that are consistent with n and $m_{l}$ values:

l=1 or 2

Therefore, the allowable condition is n=3, l=1, $m_{l}$ =-1.

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4 0

1 year ago