Busy. Please wait.
or

show password
Forgot Password?

Don't have an account?  Sign up 
or

Username is available taken
show password

why


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.


Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.

Remove Ads
Don't know
Know
remaining cards
Save
0:01
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
Retries:
restart all cards




share
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

AQA A1 Radicals

AQA Radical reactions of Alkanes and Ozone Depletion

QuestionAnswer
What is the effect of Infra Red radiation on a molecule? BONDS vibrate MORE
What is the effect of UltraViolet Radiation on a bond? BONDS split homolytically, producing 2 radicals
Describe in detail the effect of increased concentration of CO2 in the atmosphere? C=O BONDS absorb IR energy; so the bonds vibrate MORE; the kinetic energy is passed on to colliding molecules; increased concentration of CO2 means more IR absorbed and ...more kinetic energy passed on; overall effect is warming up of the atmosphere
Explain why CFC are not split until the Stratosphere, but not in the troposphere the UV radiation in the troposphere has not got a frequency HIGH enough to split the bonds
CHALLENGE: Explain why CFC are damaging the Ozone layer but Bromo compounds are not C-Br BOND is weaker/lower bond enthalpy so can broken by low energy radiation/low frequency UV which exists in the troposphere; C-Cl and C-F BONDS require high energy UV which is only found in the stratosphere
Describe why CFC are damaging the ozone layer In the stratosphere, C-Cl BONDS absorb HIGH ENERGY UV radiation; the BOND splits homolytically to form Cl radicals; Cl radicals combine with Ozone to form Oxygen MOLECULE and oxygen RADICAL; O* combines wi; Cl* are regenerated=act as catalyst
Define propagation step When a radical reacts with a molecule forms a different radical
Define Termination step When two radical combine together to form a molecule
Define a radical A species (atom or molecule) with an unpaired electron
Which bond has the highest bond enthalpy? C-Br or C-Cl? C-Cl
Write the equation to show the homolytic fission of BromoTriChloroMethane F3C-Br --> F3C* + *Br Show ALL bonds; the bond that breaks first here is the C-Br as it is the weakest
What TYPE of particles are formed by heterolytic fission? ions
What TYPE of particles are formed by homolytic fission? radicals
State uses of CFCs and explain the uses by referring to their property solvent, because they have low boiling point and refrigerant because they are non-flammable and non-toxic
What is homolytic fission? When a covalent bond splits with each atom taking one electron; forming thus two radicals
Write the equation of the MonoBromination of Ethane Br-Br + CH3-CH3 --> CH3-CH2Br + H-Br
Write the equation for the initiation reaction during the MonoBromination of Ethane Br-Br --light--> Br. + .Br
Write the equation for the first propagation reaction during the MonoBromination of Ethane Br. + CH3-CH3 --> CH3-CH2. + H-Br
Write the equation for the second propagation reaction during the MonoBromination of Ethane CH3-CH2. + Br-Br --> CH3-CH2Br + Br.
What is the role of Bromine radical in the Bromination of Ethane? Bromine radicals act as catalysts
Write a possible by-product of the MonoBromination of Ethane CH3-CH2-CH2-CH3 (in the termination step) or Br-CH2-CH2-Br (further substitution of the Monobromoethane)
Write the equation for the termination reaction during the MonoBromination of Ethane CH3-CH2. + CH3-CH2. --> CH3-CH2-CH2-CH3
How does Ozone protect us from harmful UV radiation? Ozone molecule absorbs the UV energy and splits into O2 and Oxygen radical; the Oxygen radical reacts with O2 to reform O3 and releases heat.
What does the sign <=> mean? that the reaction is in equilibrium: the rate of the forward reaction is the same as the RATE of the backward reaction and the concentration of the chemicals stay the same
Define an equilibrium When the rate of the forward reaction is the same as the RATE of the backward reaction and the concentration of the chemicals stay the same
What is the effect of UV radiation on humans? Skin cancer
What is the troposphere? The lowest layer of the Earth's atmosphere (near the surface)
What is the stratosphere? The layer of the Atmosphere that contains Ozone
Write the equations for the two propagation steps where Ozone is removed by Chlorine radicals Cl. + O3 --> ClO. + O2 AND ClO. + O --> Cl. + O2
Write the equations for the two propagation steps where Ozone is removed by Nitrogen Monoxide NO. + O3 --> NO2. + O2 AND NO2. + O --> NO. + O2
What is the overall equation for this propagation reaction? NO. + O3 --> NO2. + O2 AND NO2. + O --> NO. + O2 add all the reactants on the left and all the products on the right NO. + O3 + NO2. + O --> NO2. + O2 + NO. + O2 simplify to O3 + O --> 2 O2
What is the overall equation for this propagation reaction? Cl. + O3 --> ClO. + O2 AND ClO. + O --> Cl. + O2 add all the reactants on the left and all the products on the right Cl. + O3 + ClO. + O --> ClO. + O2 + Cl. + O2 simplify to O3 + O --> 2 O2
What is the overall equation for this propagation reaction? Br. + CH3-CH3 --> CH3-CH2. + H-Br AND CH3-CH2. + Br-Br --> CH3-CH2Br + Br. add all the reactants on the left and all the products on the right Br. + CH3-CH3 + CH3-CH2. + Br-Br --> CH3-CH2. + H-Br + CH3-CH2Br + Br. simplify to Br-Br + CH3-CH3 --> CH3-CH2Br + H-Br
Created by: UrsulineChem