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posledela
3 years ago
11

If Plank's constant is 6.6 x 10(-34) J/Hz, then what is the approximate frequency of a photon having an energy of 3 x 10(-19) Jo

ules?
Chemistry
1 answer:
fomenos3 years ago
8 0
Energy of photon = hc/λ . frequency = c/λ. so energy = h x frequency. frequency = energy/h = 3x10^-19 / 6.6 x 10^-34 = 4.54 x 10^14 Hz
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Can the pH scale be utilized for all acids (Arrhenius, Bronsted-Lowry, and Lewis)? Give examples of substances from each definit
CaHeK987 [17]

Answer:

No

Explanation:

The pH scale is a scale graduated from 0-14 which shows the degree of acidity of alkalinity of a substance. The pH scale is graduated in such a way that 0-6.9 indicates acidity, 7.0 indicate a neutral substance, while a pH of 8-14 indicates alkalinity respectively.

There are three main definitions of acids/bases

- Arrhenius definition

-Brownstead-Lowry definition

-Lewis definition

Arrhenius explains acids as any substance that produces hydrogen ions as its only positive ion in solution while a base produces hydroxide ions as its only negative ion in solution. The pH scale is based on corresponding values of pH derived from aqueous solutions of these substances.

However, not all acids/bases produces hydrogen or hydroxide ions in solution. Brownstead-Lowry definition of acids and Lewis definition of acids could be extended to nonaqueous media where the pH can not be measured as there are no hydrogen or hydroxide ions present in the solution.

This implies that pH measurement may not apply to acids/bases in the all the categories of acids/bases hence it can not be utilized for all acids and bases.

Arrhenius - sodium carbonate

Brownstead-Lowry - concentrated HF

Lewis acid - AlCl3

6 0
3 years ago
Your bedroom gets direct sunlight through a window during the hottest times of the day. you ask your mom to turn down the thermo
Kipish [7]

If you take your mom's advice, a. the room will be cooled by minimizing heat transfer by reflection.

The Sun is heating your room by its <em>radiation</em>.

The aluminium foil is shiny, so it reflects the Sun’s radiation back outside the window.

<em>Convection</em> is the transfer of heat caused by the air moving around in your room.

<em>Conduction</em> occurs only when a hot object is in contact with a cooler object.

5 0
2 years ago
Metallic character is highest in the
krok68 [10]

Answer:

a

Explanation:

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5 0
3 years ago
How long must $542 be invested at a rate of 7% to earn $303.52 in interest
yulyashka [42]

The number of years that must be invested at  a rate of 7 % to earn$ 303.52 in interest is

    8 years

 <em><u>calculation</u></em>

  • <em><u> </u></em><em>by use of  the formula       A = P (1+  rt) </em>
  • <em>  where :  A  is the final amount  =  542 + 303.52  =$ 845.52</em>

<em>                    P  is the principal   money to be invested =  $ 542</em>

<em>                        r= rate= 7/100=0.07</em>

<em>                       t=  time required</em>

<em>=$ 845.52=$ 542( 1+  0.07 t)</em>

  • <em>open the  bracket</em>
  • <em>= $845.53= $542 + $37.94  t</em>

  • <em>like terms  together</em>

    =$  845.53 -$542  = $37.94 t

   =$303.52 =$37.94 t

  • divide both  side by  $37.94

  =  $303.52/ $   37.94  =  $37.94t/$37.94

  t=  8 years

7 0
2 years ago
Fe3O4(s) + 4H2(g)3Fe(s) + 4H2O(g) Using standard thermodynamic data at 298K, calculate the entropy change for the surroundings w
alexandr402 [8]

Answer:

dS= 1.79*169.504

j/k = 303.41 j/k

Explanation:

Fe3O4(s) + 4H2(g) --> 3Fe (s)+ 4H2O(g)

dS(Fe3O4) =146.4 j/k

dS(H2) =130.684

dS(Fe) =27.78

dS(H2O) =188.825

dSrxn = dS[product]-dS[reactants]

= 3*dS(Fe)+ 4*dS(H2O)-[1*dS(Fe3O4)+ 4dS(H2)]

= [3*27.78 +4*188.825-146.4 -4*130.684] j/k = 169.504 j/k

This is the dS for 1mole Fe3O4

for 1.79 mols Fe3O4

dS= 1.79*169.504 j/k = 303.41 j/k

7 0
3 years ago
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