Arrange the following 0.1 M solutions in order of increasing pH and state why you placed each
solution in that position:
NaCH3COO
HCl
HCN
NaOH
NH3
NaCN
KNO3
H2SO4
NH4CL
H2SO3
NaHCO3
Na3PO4
CH3COOH
The only way to do this, I think, is to calculate, on an individual basis, the pH of each of the solutions. To do that you need to recognize which are strong or weak acids, which are strong or weak bases and which are salts (and the kind of salt of each). I shall be glad to help you through this process but I don't intend to work 13 problems.
Acids:
HCl strong
HCN weak
H2SO4 1st H is strong; second is weak.
H2SO3 weak
CH3COOH weak
bases:
NaOH strong
NH3 weak
salts: (they hydrolyze)
CH3COONa CH3COO^- is a base
NaCN CN^- is a base
KNO3 neither ion is hydrolyzed
NH4Cl NH4^+ is an acid.
NaHCO3 HCO3^- is a base.
Na3PO4 PO4^-3 is a base.
To arrange the solutions in order of increasing pH, we need to determine the nature of each species and consider their respective acid-base properties. pH is a measure of the concentration of hydrogen ions (H+) in a solution, with lower pH values indicating higher acidic properties and higher pH values indicating higher basic (alkaline) properties.
Here is the order of increasing pH and the reasons for placing each solution in that position:
1. HCl: HCl is a strong acid that completely dissociates in water to form H+ ions and Cl- ions. Thus, it has the lowest pH and is the most acidic solution.
2. HCN: HCN is a weak acid that partially dissociates in water to form H+ ions and CN- ions. Since it is a weak acid, it will have a slightly higher pH than HCl but still be acidic.
3. H2SO4: H2SO4 is also a strong acid like HCl but has two acidic protons. It readily dissociates in water to form two H+ ions and one SO4 2- ion. It has a lower pH than the remaining solutions due to its strong acidic nature.
4. CH3COOH: CH3COOH is a weak acid known as acetic acid. It partially dissociates in water to form H+ ions and the acetate anion, CH3COO-. It has a slightly higher pH compared to the strong acids like HCl and H2SO4.
5. NH4Cl: NH4Cl is a salt resulting from the reaction of a weak base (NH3) and a strong acid (HCl). NH4+ can act as a weak acid, releasing H+ ions in water. As a result, it will have a slightly higher pH than CH3COOH.
6. NaCN: NaCN is a salt formed from a weak acid (HCN) and a strong base (NaOH). NaCN hydrolyzes in water to produce CN- ions, which can act as a weak base, accepting H+ ions. Therefore, it will have a slightly higher pH than NH4Cl.
7. NaCH3COO: NaCH3COO is a salt formed by the reaction of a weak acid (CH3COOH) and a strong base (NaOH). NaCH3COO hydrolyzes in water to form acetate ions (CH3COO-) and Na+. Since acetate ions can act as a weak base, it will have a higher pH than NaCN.
8. NaHCO3: NaHCO3 is sodium bicarbonate, a salt formed by the reaction of a weak acid (H2CO3, carbonic acid) and a strong base (NaOH). NaHCO3 can act as a weak base, releasing H+ ions, which results in a slightly higher pH.
9. Na3PO4: Na3PO4 is a salt formed by the reaction of a weak acid (H3PO4) and a strong base (NaOH). Na3PO4 hydrolyzes in water to produce phosphate ions (PO4 3-), which can act as a weak base. It will have a higher pH than NaHCO3.
10. NaOH: NaOH is a strong base that completely dissociates in water to form OH- ions and Na+ ions. It has a higher pH compared to the acidic solutions mentioned earlier and acts as a source of hydroxide ions.
11. NH3: NH3 is a weak base that accepts H+ ions from water to form ammonium ions (NH4+). It has a higher pH than NaOH since it acts as a weak base but still possesses basic properties.
12. Na2SO3: Na2SO3 is a salt formed by the reaction of a weak base (NaOH) and a weak acid (H2SO3). Since it is a weak acid and a weak base mixture, it will have a relatively higher pH than NH3.
13. NaCl: NaCl is neutral and does not have any acidic or basic properties. It has a pH of 7, which is considered neutral.
The order of increasing pH is as follows:
HCl < HCN < H2SO4 < CH3COOH < NH4Cl < NaCN < NaCH3COO < NaHCO3 < Na3PO4 < NaOH < NH3 < Na2SO3 < NaCl
To arrange the solutions in order of increasing pH, we need to consider the acidity or basicity of each compound. Here is the step-by-step approach for arranging the given solutions:
1. HCl: HCl is a strong acid, which completely ionizes in water to produce H+ ions. Therefore, it will have the lowest pH among the given solutions.
2. H2SO4: H2SO4 is also a strong acid, similar to HCl. It will have a lower pH compared to the rest of the solutions.
3. H2SO3: H2SO3 is a weak acid, which partially ionizes in water to produce H+ ions. Since it is weaker than HCl and H2SO4, it will have a slightly higher pH.
4. CH3COOH: CH3COOH is a weak acid, commonly known as acetic acid. It partially ionizes in water to produce H+ ions. It will have a pH higher than H2SO3.
5. NaCN: NaCN is a salt resulting from the reaction of sodium hydroxide (NaOH) and hydrogen cyanide (HCN). It is considered a basic salt and will have a pH higher than that of CH3COOH.
6. KNO3: KNO3 is a salt resulting from the reaction of potassium hydroxide (KOH) and nitric acid (HNO3). It is considered a neutral salt since both KOH and HNO3 are strong acids and bases. Its pH will be close to neutral.
7. NaCH3COO: NaCH3COO is a salt resulting from the reaction of sodium hydroxide (NaOH) and acetic acid (CH3COOH). It is considered a basic salt since NaOH is a strong base and CH3COOH is a weak acid. Its pH will be higher than KNO3.
8. NaOH: NaOH is a strong base that completely dissociates in water to produce OH- ions. It will have a higher pH compared to all the previously mentioned solutions.
9. NaHCO3: NaHCO3 is a salt resulting from the reaction of sodium hydroxide (NaOH) and carbonic acid (H2CO3). It is considered a weakly basic salt and will have a higher pH compared to NaOH.
10. NH3: NH3 is a weak base, also known as ammonia. It reacts with water to produce OH- ions, increasing the pH. Its pH will be higher than that of NaHCO3.
11. NH4Cl: NH4Cl is a salt resulting from the reaction of ammonia (NH3) and hydrochloric acid (HCl). It is considered an acidic salt due to the presence of HCl. Its pH will be lower than NH3.
12. Na3PO4: Na3PO4 is a salt resulting from the reaction of sodium hydroxide (NaOH) and phosphoric acid (H3PO4). It is considered a weakly basic salt and will have a higher pH compared to NH4Cl.
In summary, the solutions arranged in increasing order of pH are as follows:
HCl < H2SO4 < H2SO3 < CH3COOH < NaCN < KNO3 < NaCH3COO < NaOH < NaHCO3 < NH3 < NH4Cl < Na3PO4