This preview shows page 1. Sign up to view the full content.
Unformatted text preview: 52 EXPERIMENT #2 +
Today we know that H ions cannot exist in water, because a H ion is a bare proton, and +
a charge of +1 is too concentrated for such a tiny particle. Because of this, any H ion in +
water immediately combines with a H2O molecule to form a hydrated hydrogen ion, H3O + [that is, H(H2O) ], commonly called a hydronium ion. + +
H (aq) + H2O(l) ──────────────> H3O (aq) hydrogen ion water hydronium ion (proton) +
While it is a known fact that that the hydrogen ion does not exist alone, as H , but is +
stable in aqueous solution in the form of the hydronium ion, H3O , it is an accepted + +
simplification to represent the hydronium ion, H3O , as a hydrogen ion, H . In beginning courses, formulas for acids (and no other compounds except water) are written with the dissociable hydrogen atoms (acidic hydrogen atoms) first, as in HCl. H2O +
HCl(g) ──────────────> H (aq) + Cl (aq) Methane, CH4, ammonia, NH3, urea, NH2─CO─NH2, and glucose, C6H12O6, are examples of substances that are not acids, since they do not provide hydrogen ions to aqueous solutions. Their hydrogen atoms are therefore not written first in their formulas. For certain acids such as acetic acid, HC2H3O2, only the hydrogen atom written first is +
capable of being released as hydrogen ion, H ; the other three hydrogen atoms do not + yield H ions in aqueous solution. +
With a slight modification (the introduction of the H3...
View Full Document