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emmasim [6.3K]
3 years ago
9

Is the reduction of copper from copper(ii) oxide by carbon exothermic or endothermic? what is the sign of the energy change?

Physics
1 answer:
Sloan [31]3 years ago
8 0

Answer;

-Exothermic reaction;

-The sign of the energy change is negative (-)

Explanation;

2CuO(s) + C(s) --> 2Cu(s) + CO2(g)  

ΔH = ΣΔHf(products) - ΣΔHf(reactants)  

ΔH = -393.5kJ - 2(-155.2kJ) = -83.1 kJ  

The reaction is exothermic.

-An exothermic process or reaction releases heat, causing the temperature of the immediate surroundings to rise. An endothermic process absorbs heat and cools the surroundings.

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a car traveling at a velocity of 2 m/s undergoes an acceleration of 4.5 m/s^2 over a distance of 340 m. How fast will it be goin
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The least possible uncertainty in an electron's velocity is, 4.32\times 10^{5}m/s

The percentage of the average speed is, 33 %

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According to the Heisenberg's uncertainty principle,

\Delta x\times \Delta p=\frac{h}{4\pi} ...........(1)

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\Delta x = uncertainty in position

\Delta p = uncertainty in momentum

h = Planck's constant

And as we know that the momentum is the product of mass and velocity of an object.

p=m\times v

or,

\Delta p=m\times \Delta v      .......(2)

Equating 1 and 2, we get:

\Delta x\times m\times \Delta v=\frac{h}{4\pi}

\Delta v=\frac{h}{4\pi \Delta x\times m}

Given:

m = mass of electron = 9.11\times 10^{-31}kg

h = Planck's constant = 6.626\times 10^{-34}Js

radius of atom = 67.0pm=67.0\times 10^{-12}m     (1pm=10^{-12}m)

\Delta x = diameter of atom = 2\times 67.0\times 10^{-12}m=134.0\times 10^{-12}m

Now put all the given values in the above formula, we get:

\Delta v=\frac{6.626\times 10^{-34}Js}{4\times 3.14\times (134.0\times 10^{-12}m)\times (9.11\times 10^{-31}kg)}

\Delta v=4.32\times 10^{5}m/s

The minimum uncertainty in an electron's velocity is, 4.32\times 10^{5}m/s

Now we have to calculate the percentage of the average speed.

Percentage of average speed = \frac{\text{Uncertainty in speed}}{\text{Average speed}}\times 100

Uncertainty in speed = 4.32\times 10^{5}m/s

Average speed = 1.3\times 10^{6}m/s

Percentage of average speed = \frac{4.32\times 10^{5}m/s}{1.3\times 10^{6}m/s}\times 100

Percentage of average speed = 33.2 % ≈ 33 %

Thus, the percentage of the average speed is, 33 %

3 0
3 years ago
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