Answer Happy

I need to know why these calculation methods are different.
one has ''change'', but the other does not have
''change''
Does it result from the difference between strong acid or weak
acid?
Due to the degree of dissociation??
Best regards...
Learning Check ... 1) What is the pH of a 2 x 10-³ M HNO, solution? HNO, is a strong acid - 100% dissociation. HNO3(aq) + H₂O (1) H₂O* (aq) NO3 (aq) OM ом Start 0.002M End ом 0.002M 0.002M pH = -log [H] = -lg [H₂O*] = -lg (0.002) = 2.7 2) What is the pH of a 1.8 x 10-2 M Ba(OH)₂ solution? Ba(OH)₂ is a strong base - 100% dissociation Ba(OH)2 (s) Ba²+ (aq) 0.018M OM Start End OM 0.018M pH = 14 - pOH = 14.00 + + Ig(0.036) H с E (ST Calculate the pH of a 0.0010 M solution of formic acid, HCOOH (K=1.8 x 10-4). HCOOH + H₂O HCOO + H₂O* Dissociation weak and HCOOH is g forbially | cookly)+ H₂0 (1) == Hooolags + that (ag 0.0010 4X 0·0010-X +x x