Which of the following mixtures will be a buffer when dissolved in 1 liter of water?
0.10 mol Ba(OH)2 and 0.20 mol HCl
0.30 mol KCl and 0.30 mol HCl
0.40 mol NH3 and 0.40 mol HCl
0.20 mol HNO2 and 0.10 mol NaOH
0.20 mol HBr and 0.10 mol KOH
My answer is that HNO2 and NaOH will be a buffer. Would you agree?
yes
To determine which of the given mixtures will act as a buffer when dissolved in water, we need to check if they satisfy the requirements of a buffer solution. A buffer solution is a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It helps in maintaining a relatively stable pH when small amounts of acid or base are added to it.
Let's analyze each option:
1. 0.10 mol Ba(OH)2 and 0.20 mol HCl:
- Ba(OH)2 is not a weak acid or a weak base, so it cannot act as a buffer.
- HCl is a strong acid, so it does not have a conjugate base.
2. 0.30 mol KCl and 0.30 mol HCl:
- KCl is a salt and does not contain any weak acid or base, so it cannot act as a buffer.
- HCl is a strong acid, so it does not have a conjugate base.
3. 0.40 mol NH3 and 0.40 mol HCl:
- NH3 is a weak base and can act as a buffer if combined with its conjugate acid.
- HCl is a strong acid, so it does not have a conjugate base.
4. 0.20 mol HNO2 and 0.10 mol NaOH:
- HNO2 is a weak acid and can act as a buffer when combined with its conjugate base.
- NaOH is a strong base, so it does not have a conjugate acid.
5. 0.20 mol HBr and 0.10 mol KOH:
- HBr is a strong acid, so it does not have a conjugate base.
- KOH is a strong base, so it does not have a conjugate acid.
Based on the analysis above, option 4, 0.20 mol HNO2 and 0.10 mol NaOH, is the correct answer. HNO2 is a weak acid, while NaOH is a strong base. When combined, they form a buffer solution.
Therefore, I agree with your answer that HNO2 and NaOH will act as a buffer when dissolved in water.