In fact, s ome magnesium hydroxide is formed in the reaction, but as the species is almost insoluble, few hydroxide ions actually dissolve. The reaction is shown below:. Reaction with acids: Magnesium oxide reacts with acids as predicted for a simple metal oxide. For example, it reacts with warm dilute hydrochloric acid to give magnesium chloride solution. Describing the properties of aluminum oxide can be confusing because it exists in a number of different forms.
One of those forms is very unreactive known chemically as alpha-Al 2 O 3 and is produced at high temperatures. The following reactions concern the more reactive forms of the molecule. Aluminium oxide is amphoteric. It has reactions as both a base and an acid. Reaction with water: Aluminum oxide is insoluble in water and does not react like sodium oxide and magnesium oxide.
The oxide ions are held too strongly in the solid lattice to react with the water. Reaction with acids: Aluminum oxide contains oxide ions, and thus reacts with acids in the same way sodium or magnesium oxides do. Aluminum oxide reacts with hot dilute hydrochloric acid to give aluminum chloride solution. Reaction with bases: Aluminum oxide also displays acidic properties, as shown in its reactions with bases such as sodium hydroxide. Various aluminates compounds in which the aluminum is a component in a negative ion exist, which is possible because aluminum can form covalent bonds with oxygen.
This is possible because the electronegativity difference between aluminum and oxygen is small, unlike the difference between sodium and oxygen, for example electronegativity increases across a period. Aluminum oxide reacts with hot, concentrated sodium hydroxide solution to produce a colorless solution of sodium tetrahydroxoaluminate:. Silicon is too similar in electronegativity to oxygen to form ionic bonds. Therefore, because silicon dioxide does not contain oxide ions, it has no basic properties.
In fact, it is very weakly acidic, reacting with strong bases. Reaction with water: Silicon dioxide does not react with water, due to the thermodynamic difficulty of breaking up its network covalent structure. Reaction with bases : Silicon dioxide reacts with hot, concentrated sodium hydroxide solution, forming a colorless solution of sodium silicate:. In another example of acidic silicon dioxide reacting with a base, the Blast Furnace extraction of iron, calcium oxide from limestone reacts with silicon dioxide to produce a liquid slag, calcium silicate:.
Phosphorus III oxide: Phosphorus III oxide reacts with cold water to produce a solution of the weak acid, H 3 PO 3 —known as phosphorous acid, orthophosphorous acid or phosphonic acid:.
The protons remain associated until water is added; even then, because phosphorous acid is a weak acid, few acid molecules are deprotonated. Phosphorous acid has a pK a of 2. Phosphorus III oxide is unlikely to be reacted directly with a base.
In phosphorous acid, the two hydrogen atoms in the -OH groups are acidic, but the third hydrogen atom is not. Therefore, there are two possible reactions with a base like sodium hydroxide, depending on the amount of base added:. In the first reaction, only one of the protons reacts with the hydroxide ions from the base. In the second case using twice as much sodium hydroxide , both protons react. If instead phosphorus III oxide is reacted directly with sodium hydroxide solution, the same salts are possible:.
Phosphorus V oxide: Phosphorus V oxide reacts violently with water to give a solution containing a mixture of acids, the nature of which depends on the reaction conditions. To start off, please go through my answer to this question: Why is chromate stable in basic medium and dichromate stable in acidic medium? Essentially, the book talks about determining the type of reactivity of inorganic molecules by looking at their structures.
While the completely correct mechanism can only be found out experimentally, we can get a probable mechanism by employing an arrow-pushing approach, and that should at least mirror the actual pathway to a sufficient extent, if not entirely.
This structure now possesses some unique properties. The products for these reactions can be verified for aluminium and gallium oxides from their Wikipedia pages respectively. So we can see that one major reason for the amphoteric nature of oxides can be their bridged structures, which allows them to react with both acids and bases as illustrated above.
So, I would expect this oxide to atleast have some amphoteric properties. This is indeed the case, as stated here for indium hydroxide since hydroxides are simply hydrated forms of their oxides, we can expect a similar nature for indium oxide as well :. The result indicated conclusively that In OH 3 is only slightly amphoteric, being much more basic than acidic. Also, on the Wikipedia page for indium oxide it clearly states that this oxide is soluble in acids but not in alkali.
This is pretty much expected because when you move down a group, the elements tend to become more metallic in nature, and hence their oxides tend to become more basic as well. Hence, an amphoteric oxide slightly tending towards the basic end seems reasonable for indium III oxide. This indeed is the case as can be seen here. Hence, one would expect this oxide to simply become more basic than the other group members as it is an oxide of the lower-most element of the group and not show much signs of an amphoteric nature.
This matches with what is stated here. Before wrapping up the answer, I would like to re-iterate a point I made at the beginning of the answer:. All these pathways are simply possible mechanisms, and there is no way of knowing whether they are completely correct or not without performing experiments. However, they are highly probable propositions, and you can expect these pathways to represent the actual mechanisms to a good approximation.
Metal hydroxides are basic in water. Non-metal oxides are acids in water. The limit between metals and non-metals is a sort of staircase going through the periodic table from the middle of the first line to the lower corner at the right-hand side. Aluminium touches this staircase. This is why Aluminium behaves like a metal and like a non-metal, and why aluminium oxide can react with acids and with bases.
Tin Sn has the same property. Sign up to join this community. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email.
Notify me of new posts via email. Create a free website or blog at WordPress. Topics Bonding Why impurities decrease m. How Mr affects m. Why must oxidizing agent be in excess during oxidation of alcohol to acid? Is esterification a redox reaction? Chemistry of Soap An excellent post by Mr. Search Search. But, we know that metal oxides are basic. So, what gives rise to this special property? In order to answer this question, we first need to understand why metal oxides are basic.
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