What are nucleic acids made up of?

What is hydrogen role in nuclear fusion?

kicyunya [14]

Answer:

Fusion powers the Sun and stars as hydrogen atoms fuse together to form helium, and matter is converted into energy. Hydrogen, heated to very high temperatures changes from a gas to a plasma in which the negatively-charged electrons are separated from the positively-charged atomic nuclei (ions).

I hope it's helpful!

6 0

3 years ago

Which molecule has polar bonding and is nonpolar? A. H2O B. BF3 C. NH3 D. NCl3 E. CH2Cl2

Marina CMI [18]

Answer:

B. BF₃

Explanation:

All the molecules have polar bonds, but a molecule will be nonpolar if the molecule has the symmetry that makes the bond dipoles cancel.

To make the decision, we must

Draw the Lewis structure
Assign the VSEPR electron geometry
Determine the molecular shape.
Examine the symmetry of the molecule

===============

A. Water

Lewis structure = H-O-H (2 bonding pairs, 2 lone pairs)

Electron geometry = AX₂E₂ tetrahedral

Molecular geometry = bent

Symmetry (see Figure A): The two O-H bonds are polar, with their negative ends pointing towards the O. The horizontal components of the bond dipoles cancel, but the vertical components reinforce each other and give an upward pointing molecular dipole. This is a polar molecule with polar bonds.

===============

B. Boron trifluoride

Lewis structure = BF₃ (3 bonding pairs)

Electron geometry = AX₃, trigonal planar

Molecular geometry = trigonal planar

Symmetry (see Figure B): The three B-F bonds are polar, with their negative ends pointing towards the F. The horizontal components of the bond dipoles cancel, but the vertical components of the two downward -pointing dipoles reinforce each other and give a resultant that is equal and opposite to the upward dipole. Thus, the bond dipoles cancel. This is a nonpolar molecule with polar bonds.

===============

C. Ammonia

Lewis structure = :NH₃ (3 bonding pairs, 1 lone pairs)

Electron geometry = AX₃E, tetrahedral

Molecular geometry = trigonal pyramidal

Symmetry (see Figure C): The three N-H bonds are polar, with their negative ends pointing towards the N. The horizontal components of the bond dipoles cancel, but the vertical components reinforce each other and give an upward pointing molecular dipole. This is a polar molecule with polar bonds.

===============

D. Nitrogen trichloride

Lewis structure = :NCl₃ (3 bonding pairs, 1 lone pair)

Electron geometry = AX₃E, tetrahedral

Molecular geometry = trigonal pyramidal

Symmetry (see Figure D): The three N-Cl bonds are polar, with their negative ends pointing towards the Cl. The horizontal components of the bond dipoles cancel, but the vertical components reinforce each other and give a downward pointing molecular dipole. This is a polar molecule with polar bonds.

===============

E. Dichloromethane

Lewis structure = H₂CCl₂ (4 bonding pairs)

Electron geometry = AX₄, tetrahedral

Molecular geometry = tetrahedral

Symmetry (see Figure E): The two C-H bonds are nonpolar, but the two C-Cl bonds are polar with their negative ends pointing towards the Cl. The horizontal components of the bond dipoles cancel, but the vertical components reinforce each other and give a downward pointing molecular dipole. This is a polar molecule with polar bonds.

3 0

3 years ago

At 298 K, what is the Gibbs free energy change (ΔG) for the following reaction?

9966 [12]

Answer:

(a). The Gibbs free energy change is 2.895 kJ and its positive.

(b). The Gibbs free energy change is 34.59 J/mole

(c). The pressure is 14924 atm.

(d). The Gibbs free energy of diamond relative to graphite is 4912 J.

Explanation:

Given that,

Temperature = 298 K

Suppose, density of graphite is 2.25 g/cm³ and density of diamond is 3.51 g/cm³.

$\Delta H\ for\ diamond = 1.897 kJ/mol$

$\Delta H\ for\ graphite = 0 kJ/mol$

$\Delta S\ for\ diamond = 2.38 J/(K mol)$

$\Delta S\ for\ graphite = 5.73 J/(K mol)$

(a) We need to calculate the value of $\Delta G$ for diamond

Using formula of Gibbs free energy change

$\Delta G=\Delta H-T\Delta S$

Put the value into the formula

$\Delta G= (1897-0)-298\times(2.38-5.73)$

$\Delta G=2895.3$

$\Delta G=2.895\ kJ$

The Gibbs free energy change is positive.

(b). When it is compressed isothermally from 1 atm to 1000 atm

We need to calculate the change of Gibbs free energy of diamond

Using formula of gibbs free energy

$\Delta S=V\times\Delta P$

$\Delta S=\dfrac{m}{\rho}\times\Delta P$

Put the value into the formula

$\Delta S=\dfrac{12\times10^{-6}}{3.51}\times999\times10130$

$\Delta S=34.59\ J/mole$

(c). Assuming that graphite and diamond are incompressible

We need to calculate the pressure

Using formula of Gibbs free energy

$\beta= \Delta G_{g}+\Delta G+\Delta G_{d}$

$\beta=V(-\Delta P_{g})+\Delta G+V\Delta P_{d}$

$\beta=\Delta P(V_{d}-V_{g})+\Delta G$

Put the value into the formula

$0=\Delta P(\dfrac{12\times10^{-6}}{3.51}-\dfrac{12\times10^{-6}}{2.25})\times10130+2895.3$

$0=-0.0194\Delta P+2895.3$

$\Delta P=\dfrac{2895.3}{0.0194}$

$\Delta P=14924\ atm$

(d). Here, $C_{p}=0$

So, The value of $\Delta H$ and $\Delta S$ at 900 k will be equal at 298 K

We need to calculate the Gibbs free energy of diamond relative to graphite

Using formula of Gibbs free energy

$\Delta G=\Delta H-T\Delta S$

Put the value into the formula

$\Delta G=(1897-0)-900\times(2.38-5.73)$

$\Delta G=4912\ J$

Hence, (a). The Gibbs free energy change is 2.895 kJ and its positive.

(b). The Gibbs free energy change is 34.59 J/mole

(c). The pressure is 14924 atm.

(d). The Gibbs free energy of diamond relative to graphite is 4912 J.

7 0

3 years ago

Question 107 points)

____ [38]

Answer:

Evaporation from the hydrosphere provides the medium for cloud and rain formation in the atmosphere. The atmosphere brings back rainwater to the hydrosphere. The atmosphere provides the geosphere with heat and energy needed for rock breakdown and erosion. The geosphere, in turn, reflects the sun's energy back into the atmosphere.

Explanation:

4 0

3 years ago

You have decided to test the effects of five garden fertilizers by applying some of each to five separate rows of radishes. what

attashe74 [19]

You are testing which fertilizer makes the radishes grow the fastest.

factors you should control: sunlight exposure, water amount, fertilizer amount.

Measure: check the rows of radishes to see how much each row has grown in comparison to the others. Whichever row with the healthiest radishes has the best fertilizer.

5 0

3 years ago