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2 years ago

Vitamin D is produced in the skin when 7-dehydrocholesterol reacts with UVB rays (ultraviolet B) having wavelengths between

Chemistry

1 answer:

goblinko [34]2 years ago

8 0

The energy range expected is 6.6 × 10^-19 J < E < 7.33 × 10^-19 J

The energy of the photon is given by;

E = hc/λ

E = energy of the photon

h = Plank's constant

c = speed of light

λ = wavelength of light

For the upper boundary range;

E = ?

h = 6.6 × 10^-34 Js

c = 3 × 10^8 m/s

λ = 270 × 10^-9

E = 6.6 × 10^-34 Js × 3 × 10^8 m/s / 270 × 10^-9

E = 7.33 × 10^-19 J

For the lower range;

E = ?

h = 6.6 × 10^-34 Js

c = 3 × 10^8 m/s

λ =300 × 10^-9

E = 6.6 × 10^-34 Js × 3 × 10^8 m/s / 300 × 10^-9

E = 6.6 × 10^-19 J

Hence, the energy range 6.6 × 10^-19 J < E < 7.33 × 10^-19 J

Learn more: brainly.com/question/24857760

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You are given the following three half-reactions:(1) Fe³⁺(aq) + e⁻ ⇄ Fe²⁺(aq) (2) Fe²⁺(aq) +2e⁻ ⇄ Fe(s) (3) Fe³⁺(aq) +3e⁻ ⇄ Fe(s

RideAnS [48]

The E°half-cell of the (3) is 0.33 volts .

Given,

(1) Fe3+(aq) +e =Fe2+(aq)

(2) Fe2+(aq) +2e = Fe(s)

(3) Fe3+(aq) +3e = Fe(s)

We know ,

E° half-cell of (1) is 0.77 volts .

E° half cell of ( 2) is -0.44 volts .

By resolving or adding equation 1 and 2 we will get (3) ,

Thus , the value of the E° half cell of (3) is given by ,

E°cell = E° half-cell of (1 ) + E° half-cell of (2 ) = 0.77-0.44 = 0.33 volts

Hence the E° half-cell of ( 3 ) is 0.33 volts .

<h3>What is cell potential? </h3>

It is the difference between the electrode potentials of two half cells.

it also defined as the force which causes the flow of electrons from one electrode to the another and thus results in the flow of current.

Ecell = E( cathode) - E ( anode)

<h3>What is electrode potential ? </h3>

The tendency of the electrode to lose of gain electrons is called as electrode potential.

Learn more about cell potential here :

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4 0

1 year ago

if i add 25 ml of water to 135 ml of a 0.25 M NaOH solution what will the molarity of the diluted solution be

DENIUS [597]

Answer:

0.21 M. (2 sig. fig.)

Explanation:

The molarity of a solution is the number of moles of the solute in each liter of the solution. The unit for molarity is M. One M equals to one mole per liter.

How many moles of NaOH in the original solution?

$n = c \cdot V$ ,

where

$n$ is the number of moles of the solute in the solution.
$c$ is the concentration of the solution. $c = 0.25 \;\text{M} = 0.25\;\text{mol}\cdot\textbf{L}^{-1}$ for the initial solution.
$V$ is the volume of the solution. For the initial solution, $V = 135\;\textbf{mL} = 0.135\;\textbf{L}$ for the initial solution.

$n = c\cdot V = 0.25\;\text{mol}\cdot\textbf{L}^{-1} \times 0.135\;\textbf{L} = 0.03375\;\text{mol}$ .

What's the concentration of the diluted solution?

$\displaystyle c = \frac{n}{V}$ .

$n$ is the number of solute in the solution. Diluting the solution does not influence the value of $n$ . $n = 0.03375\;\text{mol}$ for the diluted solution.
Volume of the diluted solution: $25\;\text{mL} + 135\;\text{mL} = 160\;\textbf{mL} = 0.160\;\textbf{L}$ .

Concentration of the diluted solution:

$\displaystyle c = \frac{n}{V} = \frac{0.03375\;\text{mol}}{0.160\;\textbf{L}} = 0.021\;\text{mol}\cdot\textbf{L}^{-1} = 0.021\;\text{M}$ .

The least significant number in the question comes with 2 sig. fig. Keep more sig. fig. than that in calculations but round the final result to 2 sig. fig. Hence the result: 0.021 M.

8 0

3 years ago

Read 2 more answers

What is the difference between an Isotope and an Allotrope?

Kaylis [27]

Allotropes are elements on the periodic table that have more than one crystalline form . There are three forms of the element carbon : Diamond, Graphite, and Fullerenes. Isotopes are atoms of the same element with the same atomic number but have a different mass number.

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3 years ago

How do water molecules move away from their H-O-H configuration to become new molecules?

maksim [4K]

Answer:

A water molecule is consists of two hydrogen atom, each bound to the central oxygen atom through a covalent chemical bond.

Water molecules can form new molecules by moving away from their H-O-H configuration due to thermal motions and rotations. <u>Thermal motions and rotations break the individual hydrogen bonds and change the H-O-H configuration influenced by the temperature and pressure.</u>

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3 years ago

Write the autoionization reaction for methanol, ch3oh.

aliina [53]

Autoionization Reactions are those reactions in which ions or molecules ionizes spontaneously without adding any external reagent.

For Example,
Autoionization of water.

H₂O + H₂O ⇆ H₃O⁺ + OH⁻

Autoionization reaction of Methanol is shown below,

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4 years ago