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taurus [48]
3 years ago
13

Why did improvements in agriculture lead to the growth of cities?

Chemistry
1 answer:
Marina86 [1]3 years ago
4 0
It strengthened the economy and made more people want to live there so the cities grew
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Consider the following reaction:C2H4(g) + F2(g) -----------> C2H4F2(g) Delta H = -549 kJEstimate the carbon-fluorine bond ene
frutty [35]

Answer:

Bond energy of carbon-fluorine bond is 485 kJ/mol

Explanation:

Enthalpy change for a reaction,  is given as:

\Delta H_{rxn}=\sum [n_{i}\times (E_{bond})_{i}]-\sum [n_{j}\times (E_{bond})_{j}]

Where (E_{bond})_{i}  and (E_{bond})_{j} represents average bond energy in breaking "i" th bond and forming "j" th bond respectively.n_{i} and n_{j} are number of moles of bond break and form respectively.

In this reaction, one mol of C=C, four moles of C-H and one mol of F-F bonds are broken. One mol of C-C bond, four moles of C-H bonds and two moles of C-F bonds are formed

So, -549kJ=(1mol\times 614kJ/mo)+(4mol\times E_{C-H})+(1mol\times 154kJ/mol)-(1mol\times 347kJ/mol)-(4mol\times E_{C-H})-(2mol\times E_{C-F})

or, -549kJ=(1mol\times 614kJ/mo)+(1mol\times 154kJ/mol)-(1mol\times 347kJ/mol)-(2mol\times E_{C-F})

or, E_{C-F}=485kJ/mol

So bond energy of carbon-fluorine bond is 485 kJ/mol

8 0
3 years ago
Answer it answer it answer it
Archy [21]

Answer:

A

Explanation:

A chemical change is when a new substance is created, which often has its own chemical properties, so A is the correct answer.

4 0
3 years ago
Jack is playing with a Newton's cradle. As he lifts one ball to position A and drops it, it impacts the other balls at position
svetlana [45]

Answer:

Newton's Cradle is a neat way to demonstrate the principle of the CONSERVATION OF MOMENTUM.

What happens here is when the ball on one end of the cradle is swung and it hits the other balls that are motionless, or stationary, the momentum of the swinging ball is transferred to the next ball upon impact.

Momentum is not lost in this action, what happens when it hits the next ball, the momentum is transferred to the next one, and then the next, and the the next, till it reaches the last ball on the other end. Since nothing is next to the last ball, it pushes the ball upwards, which will swing down and repeat the process going the other way.

This also demonstrates the CONSERVATION OF ENERGY. As you will see, the energy continues to move through the other balls, passing it from one ball to the other, which keeps this constantly moving.

8 0
3 years ago
Which of the following reactions are possible if sodium is more reactive than aluminum, 3 iron, and lead?
Deffense [45]

Answer:

Reaction I: Sodium + Aluminum chloride →Sodium chloride + Aluminum

Explanation:

Sodium being more reactive means that it will take the place of aluminium in whats called a displacement reaction and form.

Sodium chloride + Aluminum

8 0
3 years ago
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Which process occurs in an operating voltaic cell ?
Alex
Please identify and specify the question please!
8 0
3 years ago
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