Audaciity Posted October 31, 2009 Share Posted October 31, 2009 (edited) 1.(a) Define reduction (Give three different definitions) 1.(b) Define oxidation (Give three different definitions) 15. A dry cell has a limited life. Describe two possible reasons why this may be. For question 1, I believe I know two definitions for both terms: Oxidation is a loss of electrons in a redox reaction; Reduction is a gain of electrons in a redox reaction; Oxidation is the addition of oxygen to a substance; Reduction is the removal of oxygen from a substance. If those are right, I'm confused about the third. Thank you in advance. Edited October 31, 2009 by Audaciity Link to comment Share on other sites More sharing options...
mooeypoo Posted October 31, 2009 Share Posted October 31, 2009 Moved to Homework Help so you can get the help you need. Welcome to the forum! Link to comment Share on other sites More sharing options...
Fuzzwood Posted October 31, 2009 Share Posted October 31, 2009 Oxidation state Link to comment Share on other sites More sharing options...
DrP Posted October 31, 2009 Share Posted October 31, 2009 For question 1, I believe I know two definitions for both terms: Oxidation is a loss of electrons in a redox reaction; Reduction is a gain of electrons in a redox reaction; Oxidation is the addition of oxygen to a substance; Reduction is the removal of oxygen from a substance. If those are right, I'm confused about the third. Loss and gain of Hydrogen? Up to you to work out which way round though! Link to comment Share on other sites More sharing options...
Audaciity Posted October 31, 2009 Author Share Posted October 31, 2009 I now have 4 definitions. 1. Oxidation is the loss of electrons in a Redox reaction. 1. Reduction is the gain of electrons in a Redox reaction. 2. An increase in the oxidation state of an atom is known as oxidation. 2. A decrease in the oxidation state of an atom is known as reduction. 3. Oxidation is the addition of oxygen to a substance. 3. Reduction is the removal of oxygen from a substance. 4. Oxidation is an increase in oxidation number of an atom. 4. Reduction is a decrease in oxidation number of an atom. --- I couldn't find any evidence of the hydrogen one. --- 1 and 2 say the same thing, really. Link to comment Share on other sites More sharing options...
insane_alien Posted October 31, 2009 Share Posted October 31, 2009 3 doesn't hold all the time. redox reactions frequently don't have oxygen involved at all. and example would be reacting sodium with chlorine. the sodium is oxidized and the chlorine is reduced. oxygen wasn't involved at all. Link to comment Share on other sites More sharing options...
Audaciity Posted October 31, 2009 Author Share Posted October 31, 2009 I realise 3 is not always appropriate; however, can't I just add something like "If oxygen is involved..." at the start of the definition? Link to comment Share on other sites More sharing options...
insane_alien Posted October 31, 2009 Share Posted October 31, 2009 it still isn't a good definition, as oxygen can be the thing being oxidised Link to comment Share on other sites More sharing options...
Audaciity Posted October 31, 2009 Author Share Posted October 31, 2009 I doubt that, in the exam, they will ask for three definitions. Perhaps, two. Also, they might ask why that definition is bad. Link to comment Share on other sites More sharing options...
Mr Skeptic Posted November 1, 2009 Share Posted November 1, 2009 DrP has your answer. An H+ transfer is essentially the opposite of an electron transfer. The reason for using these is because lots of acid/base reactions work in this way, though personally I think the Lewis acid and bases are a better description, and likewise for oxidation and reduction. Link to comment Share on other sites More sharing options...
Audaciity Posted November 2, 2009 Author Share Posted November 2, 2009 A dry cell has limited life. Name two reasons why this is. 1. An electrode could become depleted in the cell, due to........? 2. ????????????? leakage??????? please help, my test is in an hour Link to comment Share on other sites More sharing options...
hermanntrude Posted November 2, 2009 Share Posted November 2, 2009 i'm sorry I can see only one reason, and that is the first law of thermodynamics. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now