write the equations for the addition reaction of ethene with bromine under the following conditions.
a) reaction in the presence of sunlight
H2C=CH2+Br2 sunlight=?
b) reaction in the absence of sunlight
H2C=CH2+Br2=?
a) The equation for the addition reaction of ethene with bromine in the presence of sunlight is:
H2C=CH2 + Br2 (sunlight) → H2C(CH2Br)CH2Br
When ethene (H2C=CH2) reacts with bromine (Br2) in the presence of sunlight, a double bond between the carbon atoms in ethene breaks and the bromine atoms are added to the carbon atoms, forming a saturated compound called 1,2-dibromoethane (H2C(CH2Br)CH2Br).
The presence of sunlight is required in this reaction as it provides the energy needed to break the double bond in ethene, making it more reactive and allowing the addition of bromine atoms.
b) The equation for the addition reaction of ethene with bromine in the absence of sunlight is:
H2C=CH2 + Br2 → H2C(CH2Br)CH2Br
In the absence of sunlight, the reaction still takes place, but at a slower rate as the absence of energy slows down the process of breaking the double bond in ethene. The overall reaction is similar to the one in the presence of sunlight, resulting in the formation of 1,2-dibromoethane (H2C(CH2Br)CH2Br).