Before class on Friday, Sept. 19
- Watch the 3 videos below (13 min, 6 min, 9 min );
- Comment or ask a question;
- Complete the notes
Our exit quiz on Friday will cover neutralization and redox reactions. Be ready!
chemistry matters
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chemistry matters 
Oxidation occurs when electrons are losing and reduction occurs when electrons are gaining. Oxidation allows us to keep track of electrons in reactions.
Questions: why did A lose electrons when it’s added with B?
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Because A is a metal. Metals usually attempt to loose electroons and try to form a Cation.
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Oxidation is losing electrons and reduction is gaining electrons. Acid and base redox reactions are single replacement reactions, In a molecular compound, the charges of all ions must normally add together to equal zero.
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From the video I learned that Oxidation occurs when electrons are lost & reduction occurs when electrons are gained. Redox occurs when electrons are transferred. If an atom is in its elemental form, the oxidation number is 0. For a monatomic ion the oxidation number equals the ionic charge. Nonmetals have negative oxidation numbers, with few exceptions, and atoms in a neutral compound have an oxidation number that sums up to 0.
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An Oxidation reaction occurs when electrons are lost. A reduction reaction occurs when electrons are gained.
Question: Are the elements at the end of a chemical formula of a compound always negative or can it be positive?
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That would be an exception and only occur with a weird,long, organic formula. We usually write the positive things (cations) first, and negative things (anions) second.
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In the video I learned how oxidation and reduction (redox) reactions work along with finding the oxidation number. Figuring out the oxidation numbers requires remembering the rules such as the elemental or monatomic form of a substance.
Question: In the sample problem c) SCl2, why is the oxidation number of S is -2 when it has to equal to zero?
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In this video I learned about oxidation, reduction, oxidation numbers and redox reactions. Redox reactions are single replacement reactions where electrons are transferred. Why does the sulfur in SO4 have an oxidation number of +8 instead of +6?
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I made a mistake. It should by +6. good catch
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In lesson 2.4,I learned about oxidation reduction reactions (where electrons are transferred). In redox reaction, there must be the occurrence of oxidation (lose electrons) and reduction (gain electrons). We use oxidation numbers to help us keep track of electrons in reactions.
Question: Any elements by itself, without combining with other things, would have 0 as their oxidation number?
On problem e of the packet, SO4, because it is polyatomic ion, the sum of the oxidation numbers would have to equal to the charge of the ion, right? So, if O4 have -8 and the ion charge is -2, shouldn’t S be 6 instead of 8 here?
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That is correct. S would be +6 so the total charge would equal -2. Good catch!
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I learned about redox reactions. The way to remember the difference between oxidation and reduction is OIL RIG. There are rules we have to remember when writing oxidation numbers.
Question: When we were determining the oxidation numbers, in D was the 2 after Na supposed to be there?
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From the video i learned that Oxidation is losing electrons, while reduction is the gaining of electrons. Redox( Acid and base) Reactions are both Single Replacement.
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I learned about the oxidation, the losing of electrons, and reduction, the gaining of electrons, in these videos.I also learned how to find the oxidation number of atoms.
Why did you have a subscript for the net ionic equation for the last problem? Why wasn’t the charge written for zinc and hydrogen (the same problem)?
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In these videos we learned about oxidation and reduction and redox reactions. Oxidation Is losing an electron, whereas reduction is gaining an electron. In a redox, oxidation and redunction occurs so electrons are tramsferred. We also learned oxidation number identification and some rules.
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