What is the oxidation state of Cr in each compound? c. Cr2O3

Video transcript

All right. Hi, everyone. So this question says to identify the chemical formula of the substance below and indicate its group five A elements. Oxidation number. The compound in question being dionysian tetroxide. Option A says N 204 with an oxidation state of positive four. Option B says N 208 with an oxidation state of positive eight. Option C says no 10 with an oxidation state of positive 10. And option D says N 305 with an oxidation state of positive three. So the given name of the compound is di nitrogen tetroxide. And if we consider each individual word starting with the first one, dying nitrogen indicates that there are two atoms of nitrogen indicated by the prefixed dye. Now in tetroxide, the prefix tetra indicates four. So in addition to having two nitrogens, I have four oxygens as well. Meaning my chemical formula is N 204. So now let's find the oxidation number of the group five A element which in this case is nitrogen. So because we don't know what the oxidation number of nitrogen is going to be, I'm going to treat this as a variable for my unknown. In this case, X no recall that the oxidation state of oxygen generally is going to be negative too. Now, exceptions do apply if the compound is a peroxide or a super oxide. But in the case of Diniro Tect TRX side, those exceptions do not apply here. So oxygen is going to have an oxidation state of minus two or negative two. So recall also that when you add the oxidation states of each atom multiplied by the number of each atom you have in your compound, that sum total should be equal to the charge of your compound overall. Right? So X is equal to the oxidation state of nitrogen. And I happen to have two atoms of nitrogen, which means that in my equation, my term should be two X. And so I'm going to add two X to the oxidation state of oxygen which in this case is negative too. However, I do have four oxygen atoms. So I should be multiplying my oxidation state of negative two by four. So when I add these two terms together, I should get the charge of my compound which is zero. So here I can simplify a bit because four multiplied by negative two gives me negative eight. So my equation becomes two, X subtracted by eight equals zero. And then once I go ahead and I isolate X, I get that X is equal to positive four, which means that the oxidation state of nitrogen in di nitrogen tetroxide is positive for and there you have it. So our answer here is going to be option A in the multiple choice. The chemical formula of dacy tetroxide is N 204 in the oxidation state of the group five A element is positive for. So with that being said, thank you so very much for watching and I hope you found this helpful.