Can anyone balance and explain the reaction Cr(OH)3 + HNO3. Why does the Cr(OH)3 dissolve?

Question

Can anyone balance and explain the reaction Cr(OH)3 + HNO3. Why does the Cr(OH)3 dissolve?

Answer 1

1Cr(OH)3 +3 HNO3 --> 1Cr(NO3)3 (aq) & 3 H2O

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Why does the Cr(OH)3 dissolve, when we know that it is very insoluble, (Ksp = 1.6e-30)

actually it disappears into solution by "dissociation", & by being converted into a new material that is soluble:

because H+ remove the OH- ions forming water,

the solid Cr(OH)3 "dissociates" into Cr+3 ions & OH- ions,... to replace the OH- in solution that the acid destroyed.

HNO3 removes the OH- as fast as the Cr(OH)3 attempts to replace them, until all of the Cr(OH)3 has "dissociated".

& the remaining product will be Cr(NO3)3, which is very soluble in water

Answer 2

The reason why Cr(OH)3 dissolves in water is because it is soluble, and you would know that from following the solubility rules.