Consider the halogenation of ethene is as follows:
CH₂=CH₂(g) + X₂(g) → H₂CX-CH₂X(g)
We can expect that this reaction occurring by breaking of a C=C bond and forming of two C-X bonds.
When bond break it is endothermic and when bond is formed it is exothermic.
So we can calculate the overall enthalpy change as a sum of the required bonds in the products:
Part a)
C=C break = +611 kJ
2 C-F formed = (2 * - 552) = -1104 kJ
Δ H = + 611 - 1104 = - 493 kJ
2C-Cl formed = (2 * -339) = - 678 kJ
ΔH = + 611 - 678 = -67 kJ
2 C-Br formed = (2 * -280) = -560 kJ
ΔH = + 611 - 560 = + 51 kJ
2 C-I Formed = (2 * -209) = -418 kJ
ΔH = + 611 - 418 = + 193 kJ
Part b)
As we can see that the highest exothermic bond formed is C-F bond so from bond energies we can found that addition of fluoride is the most exothermic reaction
The correct option is C.
A Lewis dot diagram is a representation of the valence electron of an atom, which uses dot around the symbol of the atom. Chlorine has seven electrons in its outermost shell, these seven electrons are arranged in form of dot around the atom of chlorine. If you count the number of dot given in option C, you will notice that they are seven.
Answer:
2Al + 3ZnCl₂ → 3Zn + 2AlCl₃
Explanation:
Chemical equation:
Al + ZnCl₂ → Zn + AlCl₃
Balanced Chemical equation:
2Al + 3ZnCl₂ → 3Zn + 2AlCl₃
This is the example of single displacement reaction. Al displace the zinc and form aluminium chloride and zinc metal.
There are two Al three zinc and six chlorine atoms on both side of equation so it is correctly balanced.
Thus it completely follow the law of conservation of mass.
Law of conservation of mass:
According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.
This law was given by french chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
Answer:
Decomposition reaction
Explanation:
A single reactant breaking down to form 2 or more products is decomposition
Given:
Half life(t^ 1/2) :30 years
A0( initial mass of the substance): 200 mg.
Now we know that
A= A0/ [2 ^ (t/√t)]
Where A is the mass that remains after t years.
A0 is the initial mass
t is the time
t^1/2 is the half life
Substituting the given values in the above equation we get
A= [200/ 2^(t/30) ] mg
Thus the mass remaining after t years is [200/ 2^(t/30) ] mg
