Question: of the salts, NaC2H302, NaCN, NaCl, and NH4NO3, how many form neutral aqueous solutions?
How do you determine which are neutral and which do not form neutral solutions?
The technical way of saying it is that if the anion is a stronger base than water, then the solution will be basic. If the cation is a stronger acid than water, then the solution will be acid. If the cation and anion are equally strong, the solution will be neutral. Technically, I think that's tough to follow. Here is the EASY way to do it.
Look at the salt and convert the salt to its corresponding base and acid (or acid and base). Like this.
NaC2H3O2 is sodium acetate and it MUST have come from NaOH (the base) and HC2H3O2 (the acid which is acetic acid). You can see that all I've done is to split HOH with the OH (the negative charge) goes with the cation (the positive charge) to form NaOH while the H (the positive charge) went with the anion (the negative charge) (to form HC2H3O2).
Now, you know NaOH is a strong base. You know HC2H3O2 is a weak acid. Therefore, the solution will be basic (from the strong base). Purists won't like this explanation BUT it works every time. You don't know the strong acids and strong bases? No problem. Look in the back of your text and find the Ka and Kb tables for weak acids and bases. If it isn't listed, the probability is very high that it is strong. Of course, you could have a poor table but most of the common ones are listed in a decent set of tables. I
NH4Cl would be acid BECAUSE NH3 is listed in the Kb tables and HCl is not listed anywhere. So NH3 is is a weak base, HCl is a strong acid, and the solution of NH4Cl is acidic.
To determine whether a salt forms a neutral aqueous solution, you need to analyze the dissociation of the salt in water. When a salt dissolves in water, it breaks apart into its constituent ions. The nature of these ions and their respective charges determine the acidity, neutrality, or basicity of the resulting solution.
To identify which salts form neutral solutions, we need to consider the nature of the ions produced when they dissolve in water. Here's the breakdown:
1. NaC2H3O2 (Sodium Acetate):
When NaC2H3O2 dissolves in water, it dissociates into sodium ions (Na+) and acetate ions (C2H3O2-). Both of these ions are derived from the salt's neutral molecules, so the solution will be neutral.
2. NaCN (Sodium Cyanide):
When NaCN dissolves in water, it dissociates into sodium ions (Na+) and cyanide ions (CN-). The CN- ion is a conjugate base of a weak acid (HCN), so it will react with water to form hydroxide ions (OH-) and release hydrocyanic acid (HCN). Therefore, the solution will be basic, not neutral.
3. NaCl (Sodium Chloride):
When NaCl dissolves in water, it dissociates into sodium ions (Na+) and chloride ions (Cl-). Both sodium and chloride ions are derived from the salt's neutral molecules, so the solution will be neutral.
4. NH4NO3 (Ammonium Nitrate):
When NH4NO3 dissolves in water, it dissociates into ammonium ions (NH4+) and nitrate ions (NO3-). The NH4+ ion is derived from the salt's neutral molecule and is acidic in nature. It can donate a hydrogen ion (H+) in solution, making the solution acidic, not neutral.
Based on this analysis, only NaC2H3O2 and NaCl form neutral aqueous solutions, while NaCN and NH4NO3 do not.
Remember, the key to determining whether a salt forms a neutral solution is recognizing the nature of the ions it produces when it dissolves in water.