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emmasim [6.3K]
4 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]4 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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Studies of sedimentary rocks and fossils have helped scientists understand the history of Earth. How is geologic time organized
grin007 [14]
Eras and then smaller periods based on geologic and biologic events that occurred during those times. According to geological time scale, there are six eras from the beginning some periods of few eras & then period is classified into smaller units called "epoch"

In short, Your Answer would be Option B

Hope this helps!
7 0
3 years ago
Read 2 more answers
Show that the effective force constant of a series combination is given by 1keff=1k1+1k2. (Hint: For a given force, the total di
S_A_V [24]

Answer:

1keff=1k1+1k2

see further explanation

Explanation:for clarification

Show that the effective force constant of a series combination is given by 1keff=1k1+1k2. (Hint: For a given force, the total distance stretched by the equivalent single spring is the sum of the distances stretched by the springs in combination. Also, each spring must exert the same force. Do you see why?

From Hooke's law , we know that the force exerted on an elastic object is directly proportional to the extension provided that the elastic limit is not exceeded.

Now the spring is in series combination

F\alphae

F=ke

k=f/e.........*

where k is the force constant or the constant of proportionality

k=f/e

f_{eff} =f_{1} +f_{2}............................1

also for effective force constant

divide all through by extension

1) Total force is

Ft=F1+F2

Ft=k1e1+k2e2

F = k(e1+e2) 2)

Since force on the 2 springs is the same, so

k1e1=k2e2

e1=F/k1 and e2=F/k2,

and e1+e2=F/keq

Substituting e1 and e2, you get

1/keq=1/k1+1/k2

Hint: For a given force, the total distance stretched by the equivalent single spring is the sum of the distances stretched by the springs in combination.

4 0
3 years ago
If an electric wire is allowed to produce a magnetic field no larger than that of the Earth (0.503 X 104 T) at a distance of 15
dem82 [27]

Answer:

37.725 A

Explanation:

B = magnitude of the magnetic field produced by the electric wire = 0.503 x 10⁻⁴ T

r = distance from the wire where the magnetic field is noted = 15 cm = 0.15 m

i = magnitude of current flowing through the wire = ?

Magnetic field by a long wire is given as

B = \frac{\mu _{o}}{4\pi }\frac{2i}{r}

Inserting the values

0.503\times 10^{-4} = (10^{-7})\frac{2i}{0.15}

i = 37.725 A

6 0
3 years ago
Is the image formed by a plane mirror always real?<br><br>True or false?​
mafiozo [28]
This statement is false
6 0
2 years ago
The density of gold is 19 300kg/m cube. what is the mass of gold cube with the length 0.2015m?
Sergeeva-Olga [200]

Answer:

157.9 kg

Explanation:

Density: This can be defined as the ratio of the mass of a body and it's volume.

The S.I unit of density is kg/m³.

From the question,

Density = Mass/volume

D = m/v............................ Equation 1

Where D = Density of gold, m = mass of gold, v = volume of gold.

make m the subject of the equation

m = Dv.................... Equation 2

Since the gold is a cube,

v = l³................... Equation 3

Where l = length of the gold cube.

Substitute equation 3 into equation 2

m = Dl³............... Equation 4

Given: D = 19300 kg/m³, l = 0.2015 m

Substitute into equation 4

m = 19300(0.2015)³

m = 157.9 kg.

4 0
3 years ago
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