Metal Oxides, non metal oxides, K2O and Sulfur Oxide, Calcium Oxide

[MCAT guy]

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Which fertilizer MOST reduces the effects of sulfur oxide impurities deposited in the soil by a rain storm?

• K2O
• NH4NO3
• CaHPO4
• H2NCONH2

So the answer here was K2O because it is a really strong base. The reason I'm a bit confused is because a question before this was talking about the effects of CaO (calcium oxide) on soil and it said the correct answer was that the pH increases because OH- was made. I actually got this one right.

My problem in understanding is with metal oxides vs sulfur oxide. I figured that the metal oxide was basic but then I also thought the sulfur oxide would be basic, yet the sulfur oxide leads to creating both H2SO3 and H2SO4, which need to be neutralized by a base (which again was K2O, a metal oxide).

How do you know that an oxide will be basic or acidic? I guess all the metal ones are basic, does that mean all the non metal oxides will be acidic or what is it that you need to know here?

 

[Isoprop]

I guess all the metal ones are basic, does that mean all the non metal oxides will be acidic or what is it that you need to know here?

This is correct. Most metal oxides are basic because metal oxide + water = metal hydroxide. Most nonmental oxides are acidic because nonmetal oxide + water = acid. There are other reasons, but this should be good enough for the MCAT.

 

[MCAT guy]

This is correct. Most metal oxides are basic because metal oxide + water = metal hydroxide. Most nonmental oxides are acidic because nonmetal oxide + water = acid. There are other reasons, but this should be good enough for the MCAT.

Thanks for the help bro!

 

[2010premed]

do metal hydroxides and nonmetal hydroxides follow the same pattern? Ie are most metal hydroxides basic and nonmetal hydroxides acidic?

 

[Rabolisk]

Yes. One typical "nonmetal hydroxide" is sulfuric acid. They don't really product hydroxide ions, so a more common name for them is oxyacids.

 

[2010premed]

thx =)