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Vlad1618 [11]
3 years ago
12

Pennies are made of zinc coated with copper. Copper has a work function of 4.7 eV. The ozone layer blocks nearly all solar radia

tion with wavelength shorter than 320nm, but a very small amount of 200 nm light still manages to reach the Earth's surface. Can direct sunlight produce photoelectrons from a penny?
Chemistry
1 answer:
Vadim26 [7]3 years ago
4 0

Answer:

yes  it can  λ =265  nm

Explanation:

Here we will use  the relationship

   E = h c/λ  ∴   λ  = E/ hc  where

                                          h= Plank's constant

                                           c= Speed of light

                                           λ = Wavelength = ?

Substituting

note need E in J ,

E = 4.7 eV x 1.602 x 10⁻¹⁹ J/eV = 7.5 x 10⁻¹⁹ J)

λ = 7.5 x 10 ⁻¹⁹ J / (  6.626 x 10⁻³⁴ Js x 3 x 10^8) =  2.65 x 10⁻⁷ m = 2.65

=  2.65 x 10⁻⁷ m x 1 x 10⁹ nm/m = 265 nm

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The combustion of 1 mol ch4 releases 803 kj of energy. how much energy is produced from the combustion of 5.00 mol ch4.
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Answer : The energy produced from the combustion of 5 mole CH_4 is 4015KJ

Solution : Given,

Released energy = 803 KJ

The balanced combustion reaction is,

CH_4+2O_2\rightarrow CO_2+2H_2O

As per the question,

1 mole of CH_4 releases energy = 803 KJ

5 mole of CH_4 produced energy = \frac{5mole}{1mole}\times 803KJ=4015KJ

Therefore, the energy produced from the combustion of 5 mole CH_4 is 4015KJ

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The residue of coal decomposition that is used in the manufacture of steel is called
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Coke.

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3 years ago
What is the effect of decreasing concentration of sodium hydroxide ten times in standardization​
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Answer:

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Explanation:

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7 0
3 years ago
Consider the reaction to produce methanolCO(g) + 2H2 (g) <-----> CH3OHAn equilibrium mixture in a 2.00-L vessel is found t
MariettaO [177]

Answer : The value of K_c of the reaction is 10.5 and the reaction is product favored.

Explanation : Given,

Moles of CH_3OH at equilibrium = 0.0406 mole

Moles of CO at equilibrium = 0.170 mole

Moles of H_2 at equilibrium = 0.302 mole

Volume of solution = 2.00 L

First we have to calculate the concentration of CH_3OH,CO\text{ and }H_2 at equilibrium.

\text{Concentration of }CH_3OH=\frac{\text{Moles of }CH_3OH}{\text{Volume of solution}}=\frac{0.0406mole}{2.00L}=0.0203M

\text{Concentration of }CO=\frac{\text{Moles of }CO}{\text{Volume of solution}}=\frac{0.170mole}{2.00L}=0.085M

\text{Concentration of }H_2=\frac{\text{Moles of }H_2}{\text{Volume of solution}}=\frac{0.302mole}{2.00L}=0.151M

Now we have to calculate the value of equilibrium constant.

The balanced equilibrium reaction is,

CO(g)+2H_2(g)\rightleftharpoons CH_3OH(g)

The expression of equilibrium constant K_c for the reaction will be:

K_c=\frac{[CH_3OH]}{[CO][H_2]^2}

Now put all the values in this expression, we get :

K_c=\frac{(0.0203)}{(0.085)\times (0.151)^2}

K_c=10.5

Therefore, the value of K_c of the reaction is, 10.5

There are 3 conditions:

When K_{c}>1; the reaction is product favored.

When K_{c}; the reaction is reactant favored.

When K_{c}=1; the reaction is in equilibrium.

As the value of K_{c}>1. So, the reaction is product favored.

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Now look at the volcano map what type of boundary tends to give rise to volcanic activity
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Divergent and convergent plate boundaries cause volcanic activity
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