Which of the following oxides will be more soluble in acidic solution? (LO 22.14)

(a) SiO2 (b) NO2

(c) BaO (d) B2O3

Video transcript

Welcome everybody. Our next question says among the given oxides, which one is expected to exhibit greater solubility in an acidic solution. A Geo two or Germanium oxide, BS 02 or sulfur oxide, CRB 20 or rubidium oxide or DIN 203 or indium oxide. Well, what determines the solubility in an acidic solution? Well, greater solubility in an acidic solution would indicate a more basic oxide. So we're looking for the most basic oxide among these four. So what determines whether an oxide is acidic or basic? Well, we recall that oxygen can form a compound as an oxide and of course, an oxide is a binary compound with oxygen in its favorite minus two oxidation state. And so oxygen can form oxides with both metals and nonmetals. So when you have a metal oxygen compound, well, what's the distinguishing characteristic of a metal that it readily can give away electrons? So a metal oxygen compound, the metal gives away its electrons, the oxygen happily takes them and you have an ionic compound. Since it's ionic, it is basic when dissolved in water or in a strong acid, it acts as a base because it be because it can react with water as it dissolves in water, it's an ionic compound. And the H plus ions in water or an acidic solution will react with that O to minus anion to make water. So that we can also have oxides that are nonmetal oxygen compounds. Well, these are non metals, they're not gonna give away electrons. So in these nonmetal oxygen compounds, we have covalent bonds where the two are sharing their electrons and these covalent nonmetal oxygen compounds tend to act as acids. So they are acidic. And that's because when they're dissolved in water or in a base, they can take on another bond to another oxygen atom, thereby producing H plus ions or water. When in a strong base. Well, we've seen metal nonmetal bonding and of course, we can also have sort of the in between elements, the elements in the middle. And when they form bonds with oxygen, depending on how metallic or non metallic they are, they have a more or less covalent character and are amphoteric, they can act as acids or bases depending on whether they're dissolved in an acid or a base. So we're looking for our most basic oxide. So what makes the oxides more basic a bond with a metal? So the more metallic, the other element in the oxide is the more basic the oxide will be. So we need to think about our periodic trends which direction the periodic table is more metallic well, obviously going from right to left is more metallic in character. Those elements on the left with just one or two electrons in their outer shell are more likely to give those up. And then as we go down our periodic table, we are more metallic. The farther out those outer electrons are the more easily they're given up. So therefore, we're looking for the element that is furthest to the bottom left portion of the periodic table. So with that in mind, let's look at our answer choices. Choice A Germanium oxide, we're looking at column for a row three, choice B sulfur oxide, column six A, it's right below oxygen there also row three. So we've got two non metals here. So we can probably safely go ahead and cross them off since we're looking for the most metallic choice c rubidium oxide. Well, rubidium is way over in column one. A so definitely a metal and it's down in row five. So that's looking pretty good as being down in the bottom left. But we need to look at choice D indium oxide and indium is over with the non metals in group or column three, a row five. Well, even though it's over in row three A, what we said with the non metals, it's way down in row five and therefore it is a metal. But of course, when we look at it compared to rubidium way back on the left in group one a rubidium will definitely be the more metallic in character. So our answer here, the one that we'd expect to exhibit the greater solubility and acidic solution, the most basic will be choice C RB 20 or rubidium oxide. See you in the next video.