Question

Some compounds of acidic such as AlCl3, BF3 and NH3, PH3, Na2O, CaO are of some basic nature, but they do not give H + ions or OH-ions in aqueous solution, Why ??​

Answer 1

Answer:

You hold the test charge within the electric field at certain fixed position (please refer diagram number 1).Now the test charge is moved from that fixed position to different path but finally coming to its original position representing a closed path but not a circular one.(please refer diagram number 2)

You know that a test charge in order to take inside electric field, it requires an external medium that is our hand in this case.But still as the test charge is moving it is doing work,so it must lose energy but when the test charge come back to its original position after moving a path it experiences that much force of attraction or repulsion as it was before covering a closed path hence electric field is conserved as there is no change in force of attraction or repulsion by test charge before and after covering a closed loop

Example-even if you run from a fixed point in a big field and then coming back to that fixed position. You will feel tired as you have lost energy but it is not happening in case of electric field.(please refer diagram number 3)

Please refer pic number 4 and 5 for derivation

Hope it helps

Answer 2

Some of the compound here are covalent ,which does not ionize in water , to give H+ ion.

there is always a doubt in our mind that how a compound can be acudic or basic ,if it doesn't contain H+ or OH- ion.

But it should be noted that using only that factor ,we can't determine the compound as an acidic or basic.

There are some compunds which make a water acidic when putted in it.

for example: when aluminum chloride is putted in water than the reaction is as follows

AlCl3. +H2O-----Al(OH)3 + 3HCL

here Hcl is formed when AlCl3 is putted in water,which makes the compound acidic

so.from this analysis we can say that some compunds plays a role of an acid or base,even if they doesn't contain hydrogen or hydroxyl ion

hope u get the correct explaination