1. Assign oxidation states to the elements involved in the...

1. Assign oxidation states to the elements involved in the following reactions. Indicate which are redox reactions and which are not. a) MgCO3(s) + 2H+(aq) -> Mg2+(aq) + H2O(l) + CO2(g) b) Cl2(aq) + 2Br-(aq) -> 2Cl-(aq) + Br2(aq) c) Ag(s) + 2H+(aq) + NO3-(aq) -> Ag+(aq) + H2O(l) + NO2(g) d) 2Ag+(aq) + CrO4 2-(aq) -> Ag2CrO4(s) 2. Assign oxidation states to the elements in the following redox reactions. Indicate which species is the oxidizing and which the reducing agent. a) 2NO(g) + 5H2(g) -> 2NH3(g) + 2H2O(g) b) 3Cu(s) + 8H+(aq) + 2NO3-(aq) -> 3Cu2+(aq) + 4H2O(l) + 2NO(g) c) 3Cl2(g) + 6OH-(aq) -> 5Cl-(aq) + ClO3-(aq) + 3H2O(l)

Transcript

00:01 For reaction is a redox reaction or not, we need to see if the charges of an element change from one side to the other side, so from the reactants to the products.

00:09 So we need to go through and determine what the charges are for each of these.

00:13 So we know that oxygen, unless it's by itself in its standard state as an o2 gas, it will have a charge of negative 2, 99 % of the time.

00:23 So here we have three oxygens, their charge is negative 2, that's a total of negative 6, 3 times negative 2.

00:31 This compound has an overall charge of 0, the carbon has a charge of plus 4, and that means the magnesium has a charge of plus 2.

00:39 Here we are told that hydrogen has a charge of plus 1, here we are told magnesium has a charge of plus 2.

00:46 Oxygen is minus 2, each hydrogen is plus 1, here each oxygen is minus 2, and the carbon then, that would be a total of negative 4 for this, so this carbon is a positive 4.

01:02 So in this case nothing has changed charges, so this is not a redox reaction.

01:08 Taking a look at the second equation here.

01:14 Here we have silver all by itself in its elemental state, so that means it has an overall charge of 0.

01:22 Here we are told the hydrogen has a charge of plus 1.

01:24 We know that this nitrate ion has a charge of negative 1, each oxygen is negative 2, so negative 2 times 3 is a total of negative 6.

01:35 This compound will equal negative 1, that makes our nitrogen have a charge of plus 5.

01:40 Here we are told silver has a charge of plus 1...

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