13. Which contains the same number of molecules as 22.4 liters of N2 at STP?

The transfer of energy changes the what of water

pentagon [3]

The water cycle ...........

7 0

3 years ago

Sighting along the C2-C3 bond of 2-methylbutane, the least stable conformation (Newman projection) has a total energy strain of

natima [27]

Answer:

21 KJ/mol

Explanation:

For this question, we have to start with the linear structure of 2-methylbutane. With the linear structure, we can start to propose all the Newman projections keep it in mind that the point of view is between carbons 2 and 3 (see figure 1).

Additionally, we have several energy values for each interaction present in the Newman structures:

-) Methyl-methyl gauche: 3.8 KJ/mol

-) Methyl-H eclipse: 6.0 KJ/mol

-) Methyl-methyl eclipse: 11.0 KJ/mol

-) H-H eclipse: 4.0 KJ/mol

Now, we can calculate the energy for each molecule.

Molecule A

In this molecule, we have 2 Methyl-methyl gauche interactions only, so:

(3.8x2) = 7.6 KJ/mol

Molecule B

In this molecule, we have a Methyl-methyl eclipse interaction a Methyl-H eclipse interaction and an H-H eclipse interaction, so:

(11)+(6)+(4) = 21 KJ/mol

Molecule C

In this molecule, we have 1 Methyl-methyl gauche interaction only, so:

3.8 KJ/mol

Molecule D

In this molecule, we have three Methyl-H eclipse interaction, so:

(6*3) = 18 KJ/mol

Molecule E

In this molecule, we have 1 Methyl-methyl gauche interaction only, so:

3.8 KJ/mol

Molecule F

In this molecule, we have a Methyl-methyl eclipse interaction a Methyl-H eclipse interaction and an H-H eclipse interaction, so:

(11)+(6)+(4) = 21 KJ/mol

The structures with higher energies would be less stable. In this case, structures B and F with an energy value of 21 KJ/mol (see figure 2).

I hope it helps!

3 0

3 years ago

How do I calculate the standard enthalpy change for the following reaction at 25 °C ?

ladessa [460]

MgCl2(s) + H2O(l) → MgO(s) + 2 HCl(g)

Using the standard enthalpies of formation given in the source below:

(−601.24 kJ) + (2 x −92.30 kJ) − (−641.8 kJ) − (−285.8 kJ) = +141.76 kJ
So:

MgCl2(s) + H2O(l) → MgO(s) + 2 HCl(g), ΔH = +141.76 kJ

4 0

3 years ago

True or false: nitrogen gas behaves more like an ideal gas as the temperature increases

navik [9.2K]

Is true. Nitrogen gas behaves more like an ideal gas as the temperature increases. Under normal conditions such as normal pressure and temperature conditions , most real gases behave qualitatively as an ideal gas. Many gases such as air , nitrogen , oxygen ,hydrogen , noble gases , and some heavy gases such as carbon dioxide can be treated as ideal gases within a reasonable tolerance. Generally, the removal of ideal gas conditions tends to be lower at higher temperatures and lower density (that is at lower pressure ), since the work made by the intermolecular forces is less important compared to the kinetic energy of the particles, and the size of the molecules is less important compared to the empty space between them. The ideal gas model tends to fail at lower temperatures or at high pressures, when intermolecular forces and intermolecular size are important.

5 0

3 years ago

How do high levels of alkaline phosphatase indicate a bone abnormality

ELEN [110]

Answer:

Bones make an isoenzyme called alkaline phosphatase-2 or (ALP-2). Levels of this enzyme increase when bones are growing or bone cells are active. An alkaline phosphatase bone isoenzyme test can indicate abnormal levels of bone growth that may be associated with conditions such as: Paget's disease of bone.

Explanation:

ALP (alkaline phosphatase) is an enzyme found in your bloodstream. It helps break down proteins in the body and exists in different forms, depending on where it originates.

The bones and liver are the main sources of ALP, but some is also made in your bones, intestines, pancreas, and kidneys. In pregnant women, ALP is made in the placenta.

The ALP test can be helpful in the diagnosis of bone problems such as: rickets, a weakening or softening of the bones in children that’s most commonly due to a significant deficiency of vitamin D or calcium osteomalacia, a softening of the bones in adults usually due to significant vitamin D deficiency, but also possibly due to the body’s inability to process and use vitamin D properly.

Paget’s disease of the bone, a disorder causing major problems with bone destruction and regrowth

An alkaline phosphatase level test (ALP test) measures the amount of alkaline phosphatase enzyme in your bloodstream. The test requires a simple blood draw and is often a routine part of other blood tests.

Abnormal levels of ALP in the blood most often indicate a problem with your liver, gallbladder, or bones. However, they may also indicate malnutrition, kidney cancer tumors, intestinal issues, a pancreas problem, or a serious infection.

The normal range of ALP varies from person to person and depends on ones age, blood type, gender, and pregnancy.

The normal range for serum ALP level is 20 to 140 IU/L.

The normal range runs higher in children and decreases with age.

6 0

3 years ago