An unknown salt is either KBr, NH4Cl, KCN, or K2CO3. If a 0.100 M solution of the salt is neutral, what is the identity of the salt?
It must be KBr. Neither K^+ nor Br^- are hydrolyzed in aqueous solution.
NH4Cl gives an acid solution. (NH4^+) is hydrolyzed.
HCN gives a basic solution. CN^- is hydrolyzed.
K2CO3 gives a basic solution. CO3^2- is hydrolyzed.
Well, if the solution is neutral, then I guess the salt doesn't have any strong acidic or basic properties. In other words, it's not a salt from a strong acid or a strong base. So, KCN is out of the picture because cyanide ions (CN-) are pretty good bases. And you know what they say, "When in doubt, kick out the CN-!"
That leaves us with KBr, NH4Cl, and K2CO3. Ammonium chloride (NH4Cl) is an acidic salt because ammonium ions (NH4+) can act as weak acids. So, let's ditch that one too.
That leaves us with KBr and K2CO3. Both of these are neutral salts, so it's a bit of a toss-up. But here's some food for thought: K2CO3 is made up of potassium ions (K+) and carbonate ions (CO3 2-).
Now, potassium bromide (KBr) is made up of potassium ions (K+) and bromide ions (Br-). And bromide ions, well, they're pretty chill. They're not acidic or basic. So, my money's on KBr being the mysterious salt in question.
But hey, maybe the salt just wants to keep you guessing. After all, life is full of sodium humorous surprises!
To determine the identity of the salt, we need to analyze the possible ions present in each salt and their behavior in the solution.
1. KBr: When dissolved in water, potassium bromide (KBr) dissociates into K+ and Br- ions. Both of these ions are spectator ions and do not react with water. Therefore, KBr does not affect the pH of the solution.
2. NH4Cl: Ammonium chloride (NH4Cl) dissociates into NH4+ and Cl- ions in water. The NH4+ ion can react with water in the following equilibrium:
NH4+ (aq) + H2O (l) ⇌ NH3 (aq) + H3O+ (aq)
This reaction can increase the concentration of H3O+ ions in the solution, making it acidic rather than neutral.
3. KCN: Potassium cyanide (KCN) dissociates into K+ and CN- ions in water. The CN- ion can react with water to produce hydroxide ions (OH-), increasing the concentration of OH- ions and making the solution basic rather than neutral.
4. K2CO3: Potassium carbonate (K2CO3) dissociates into 2 K+ ions and CO3^2- ions in water. The CO3^2- ion can react with water, resulting in the formation of carbonate ions (HCO3-) and hydroxide ions (OH-):
CO3^2- (aq) + H2O (l) ⇌ HCO3- (aq) + OH- (aq)
This reaction can increase the concentration of OH- ions in the solution, making it basic rather than neutral.
Based on this analysis, we can conclude that the identity of the salt is KBr because it does not affect the pH of the solution, keeping it neutral.
To determine the identity of the salt, we need to consider the behavior of its constituent ions in solution. Let's break down each salt and examine their potential reactions in water.
1. KBr: When dissolved in water, potassium bromide (KBr) dissociates into potassium ions (K⁺) and bromide ions (Br⁻). These ions do not react with water, so the solution remains neutral.
2. NH4Cl: Ammonium chloride (NH4Cl) dissociates into ammonium ions (NH4⁺) and chloride ions (Cl⁻). The ammonium ion can react with water to produce hydronium ions (H3O⁺). This results in an acidic solution, rather than a neutral one.
3. KCN: Potassium cyanide (KCN) dissociates into potassium ions (K⁺) and cyanide ions (CN⁻). The cyanide ion can react with water to produce hydroxide ions (OH⁻). This leads to a basic solution, not a neutral one.
4. K2CO3: Potassium carbonate (K2CO3) dissociates into potassium ions (K⁺) and carbonate ions (CO3²⁻). The carbonate ion reacts with water to form hydroxide ions (OH⁻). This gives a basic solution, not a neutral one.
Since KBr is the only salt that does not produce acidic or basic solutions when dissolved, it is the likely identity of the unknown salt.
To confirm this, we can also calculate the pH of the solution. Since it is neutral, the pH should be 7. Acidic solutions have a pH less than 7, while basic solutions have a pH greater than 7.
In summary, based on the behavior of the ions in solution, the identity of the unknown salt is most likely KBr.