In the following pictures of binary hydrides, ivory spheres

represent H atoms or ions, and burgundy spheres represent

atoms or ions of the other element.

(1)

(2)

(3)

(4)

(b) What is the oxidation state of hydrogen in compounds (1), (2), and (3)? What is the oxidation state of the other

element?

Video transcript

Hi, everybody. Here's our next problem. Consider the given binary hydride where the gray spheres indicate hydrogen and the green spheres indicate ions or atoms of other elements. We have three different structural illustrations given to us. And then our question says, what is the oxidation state of the hydrogen and the other other element in the hydris? And we have four answer choices and we need to identify which one correctly describes the oxidation states of the hydrogen and the other element in each of these illustrations. So let's look at each of them one by one and figure this out. First, we'll start by recalling that there are three possible types of hydride that form. So we want, we want to determine for each illustration what type of hydride we're looking at because the different hydride have different oxidation states for hydrogen. So we have ionic hydrates where a hydride ion forms an ionic bond with a metal. So this is with metals generally the group one or two a medals. And in this case, because metals of course, are characterized by their tendency to give away electrons. The hydrate ion has a minus one oxidation state. While the metal then has its positive oxidation state depending on whether it's group one or two. Then we have the covalent hydris where hydrogen forms a covalent bond with a non metals is what non metals? And in this case, hydrogen is sharing its electron and has a plus one oxidation state. While the nonmetal has a negative oxidation state, which makes sense since the nonmetals tend to accept electrons in general. And finally, we have this sort of odd in between interstitial hydris, where hydrogen atoms tend to be sort of inserted into holes between the larger transition element. And those tend to be characterized by non stoichiometry ratios. So let's look at our illustrations with this in mind, number one indicated by Roman numeral has one hydrogen and one of another element, it's just this single molecule with a 1 to 1 ratio. And when drawn like this would indicate a covalent bond between the hydrogen and the other element. So we would assume that this is a, our green element is a non metal. It's a non metal. It's in a 1 to 1 ratio, we know that our hydrogen being in a covalent hydride, H will have a plus one oxidation state. And since it's at this 1 to 1 ratio, our other atom or yeah, our other atom, it's not an ion in this case. So we'll just put, um I'm gonna put G for green in parentheses, we'll have an oxidation state of negative one. So in multiple choice, I like to first rule out anything we can on a test, you'd want to be ruling things out before you work your way through each of these illustrations. So we will do that in this case. So we're going to look at each of our answer. Choices. Choice A describes molecule one as the oxidation state of hydrogen is negative one, the other atom is plus one. So this is incorrect, we can rule out choice. A just looking at our first molecule choice B has hydrogen at plus one, the oxidation state of the other atom is minus one. So B is OK, we'll leave that alone. Choice C number one says hydrogen is plus one, the other atom is minus one. So C passes the test and D says hydrogen is minus one other atom is plus one. So D also incorrect. So we've ruled out two right away. So let's move on to structure number two. Well, this is a lattice structure. So here we would be looking at an ionic hydride since it doesn't exist as individual molecules with a bond, but these ions packed together in a lattice. And we see that it has a ratio of 1 to 1, there is one hydrogen and per every green sphere. So it's an ionic hydride, our hydrogen thus has an oxidation state of minus one. And since we have this 1 to 1 ratio, our green ion, in this case has an oxidation state, it's ionic charge of plus one. So we will look at answer choices B and C and see if we can rule one of them out. In choice B for number two, it says oxidation state of hydrogen is minus one. That's correct ox oxidation state of the other atom is plus one. And then choice C says for number two oxidation state of hydrogen is minus one oxidation state of the other is plus one. So B and C still both correct. So we need to move on to structure three se three also is showing a covalent hydrogen. It just has this one molecule depicted a single green atom with bonds to three hydrogens. So our ratio here is three greens 21 hydrogen. So because it's covalent, we know that our hydrogen has a plus one oxidation state. But since our ratio is 3 to 1, then our green atom must have an oxidation state of minus three. So let's look at our answer. Choices. Choice B says under number three, oxidation state of hydrogen is negative one oxidation state of the other atom is plus three. So this is reversed. So choice B not correct by process of elimination C is going to be our answer. And indeed, when we look at number three, it says the oxidation state of hydrogen is plus one, the other atom is minus three. So we have our answer choice here that correctly describes the oxidation state of the hydrogen and the other element that's in the hydride. And the answer is choice c number one, the oxidation state of hydrogen is plus one and the oxidation state of the other atom or ion is minus one. Number two, the oxidation state of hydrogen is minus one. The oxidation state of the other atom or ion is plus one. And number three, the oxidation state of hydrogen is plus one and the oxidation state of the other atom or ion is minus three. See you in the next video.