Which of the following pairs can be used to prepare a buffer? (select all that can apply)
a. HCl/NaCl
b. HF/KF
c. NH3/NH4Cl
d. HNO3/HNO2
e. NaNO2/HNO3
can you also please explain how they form a buffer? thank you
Buffers are solutions contg a weak acid and its salt or a weak base and its salt OR something that can form a weak acid/base and salt.
b. Has weak acid,HF, and salt KF.
c. Has weak base, NH3, and salt, NH4Cl.
e. Has NaNO2 which is the salt of a weak acid and it contains HNO3 which can form a weak acid, HNO2, from the NaNO2 salt.
a. HCl/NaCl: No, this pair cannot be used to prepare a buffer. It forms a strong acid-base combination, but not a buffer. It would simply neutralize each other.
b. HF/KF: Yes, this pair can be used to prepare a buffer. HF is a weak acid, while KF is its conjugate base. When combined in the appropriate ratio, they can resist changes in pH.
c. NH3/NH4Cl: Yes, this pair can be used to prepare a buffer. NH3 is a weak base, while NH4Cl is its conjugate acid. Together, they can resist changes in pH.
d. HNO3/HNO2: No, this pair cannot be used to prepare a buffer. Both HNO3 and HNO2 are strong acids and do not have a conjugate base to form a buffer.
e. NaNO2/HNO3: Yes, this pair can be used to prepare a buffer. NaNO2 is the salt form of a weak acid (HNO2), and when combined with HNO3 (a strong acid), it can create a buffer solution.
Buffers are able to resist changes in pH due to their ability to neutralize added acid or base. They contain a weak acid and its conjugate base or a weak base and its conjugate acid in relative amounts that ensure a stable pH. When an acid is added to a buffer, the conjugate base reacts with it to neutralize the effect on pH. Similarly, when a base is added, the weak acid reacts with it to maintain the pH level.
The pairs that can be used to prepare a buffer are:
c. NH3/NH4Cl
d. HNO3/HNO2
A buffer is a solution that resists changes in pH when small amounts of acid or base are added to it. It consists of a weak acid or base and its conjugate salt. The weak acid/base helps maintain the pH, while the conjugate salt helps neutralize any added acid or base.
In the case of NH3/NH4Cl, NH3 is a weak base (ammonia) and NH4Cl is its conjugate salt. When an acid is added to the buffer solution, the NH3 base can react with the acid to form NH4+ ions, thus preventing a large change in pH. Similarly, if a base is added, NH4Cl salt can react with the base to form NH3, again preventing a drastic change in pH.
For HNO3/HNO2, HNO2 is a weak acid (nitrous acid) and HNO3 is its conjugate salt. Again, when a base is added, the HNO2 acid can react with the base to maintain the pH. On the other hand, if an acid is added, the HNO3 salt can react with the acid to maintain the pH.
It is important to note that the other pairs mentioned in the question (a. HCl/NaCl and b. HF/KF) cannot form a buffer because they do not consist of a weak acid or a weak base with their conjugate salt. HCl, HF, NaCl, and KF are all strong acids or bases, which do not have the ability to resist changes in pH.
To determine which pairs can be used to prepare a buffer, we need to understand what a buffer is. A buffer is a solution that can resist changes in pH when a small amount of acid or base is added to it. A buffer system consists of a weak acid and its conjugate base (or a weak base and its conjugate acid) that can react with the added acid or base, minimizing the change in pH.
Now let's go through each pair and determine if they can form a buffer:
a. HCl/NaCl: This pair consists of a strong acid (HCl) and a strong base (NaCl). A buffer is formed when there is a weak acid/base present, so this pair cannot form a buffer.
b. HF/KF: This pair consists of a weak acid (HF) and its conjugate base (KF). As both HF and KF are weak, this pair can form a buffer.
c. NH3/NH4Cl: This pair consists of a weak base (NH3) and its conjugate acid (NH4Cl). Since both NH3 and NH4Cl are weak, this pair can form a buffer.
d. HNO3/HNO2: This pair consists of a strong acid (HNO3) and a weak acid (HNO2). A buffer is formed when there is a weak acid/base, so this pair cannot form a buffer.
e. NaNO2/HNO3: This pair consists of a strong base (NaNO2) and a strong acid (HNO3). A buffer is formed when there is a weak acid/base, so this pair cannot form a buffer.
In summary, the pairs that can be used to prepare a buffer are b. HF/KF and c. NH3/NH4Cl. These pairs consist of a weak acid and its conjugate base (or a weak base and its conjugate acid) which can react with added acid/base, maintaining the pH of the solution.