which of the following combinations is not suitable for making a buffer?
h3po4 and nah2po4
na2co3 and nahco3
nh4cl and nh3
nah2po4 and na2hpo4
hclo4 and naclo4
The last one and here's a tip. Don't forget where the shift key is for formulas (and starting a sentence for that matter). na2co3 doesn't mean a thing. CO is different than Co is different than co. Carbon monoxide vs cobalt vs company.
The combination that is not suitable for making a buffer is hclo4 and naclo4. A buffer is a solution that can resist changes in pH when a small amount of acid or base is added to it. In order to form a buffer solution, you need a weak acid and its conjugate base or a weak base and its conjugate acid in approximately equal concentrations.
In this case, hclo4 is a strong acid and naclo4 is a salt of a strong acid and a strong base. A strong acid does not have a conjugate base, so this combination does not provide the necessary components to form a buffer solution.
The other combinations mentioned do contain a weak acid and its conjugate base or a weak base and its conjugate acid, making them suitable for making a buffer.
To determine which combination is not suitable for making a buffer, we need to understand the characteristics of a buffer solution. A buffer solution is able to resist changes in pH by containing both a weak acid and its conjugate base, or a weak base and its conjugate acid.
Let's evaluate each combination to see if they meet the requirements:
1. H3PO4 and NaH2PO4:
- H3PO4 is a weak acid, which can act as a buffer component.
- NaH2PO4 is the conjugate base of H3PO4, making it suitable for a buffer solution.
- This combination is suitable for making a buffer.
2. Na2CO3 and NaHCO3:
- Na2CO3 is a salt of a strong base (NaOH) and a weak acid (H2CO3), making it a weakly alkaline solution. It can act as a buffer component as a weak base.
- NaHCO3 is the conjugate acid of a weak base (HCO3-), making it suitable for a buffer solution.
- This combination is suitable for making a buffer.
3. NH4Cl and NH3:
- NH4Cl is a salt of a weak base (NH3) and a strong acid (HCl), making it acidic. It can act as a buffer component as a weak acid.
- NH3 is a weak base and can act as a buffer component as a weak base.
- This combination is suitable for making a buffer.
4. NaH2PO4 and Na2HPO4:
- NaH2PO4 is a salt of a weak acid (H3PO4) and a strong base (NaOH), making it alkaline. Therefore, it cannot act as a buffer component as a weak acid.
- Na2HPO4 is the conjugate base of a weak acid (H2PO4-), making it suitable for a buffer solution.
- This combination is NOT suitable for making a buffer.
5. HClO4 and NaClO4:
- HClO4 is a strong acid, which cannot act as a buffer component.
- NaClO4 is the salt of a strong acid and a strong base, making it neutral. Therefore, it cannot act as a buffer component as a weak base or acid.
- This combination is NOT suitable for making a buffer.
Based on the analysis above, the combination that is NOT suitable for making a buffer is NaH2PO4 and Na2HPO4.