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A buffer is used to resist changes in pH and maintain a system at a near-constant pH when small amounts of acids or bases are added. A buffer is made up of a weak acid and its conjugate base (or a weak base and its conjugate acid) existing in equilibrium. When a strong acid is added to the buffer, it will be neutralized by the conjugate base and when a strong base is added to the buffer, it will be neutralized by the conjugate acid. Therefore if too much acid or base is added, the buffer can be overwhelmed and lose its buffering capability. For example: A buffer's pH is given by the Henderson-Hasselbach equation: pH = pKa + log([A-]/[HA]) where pKa is the pKa of the conjugate acid, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the conjugate acid. If 1 L of 1 M acetic acid (weak acid, pKa = 4.76) and 1 L of 1 M sodium acetate (conjugate base) is mixed to produce 2 L of acetate buffer, and the pH of this buffer is: pH = 4.76 + log(0.5M/0.5M) = 4.76 + log(1) = 4.76 (the new concentrations are 0.5 M since each 1 M solution is now in 2 L of solution) If 100 mL of 1.0 M HCl, or 0.1 mol of HCl, is added to the buffer, it is going to react with 0.1 mol of sodium acetate to produce 0.1 mol of NaCl and 0.1 mol of acetic acid. This would mean that the new conjugate base concentration is (1.0-0.1)/2 = 0.45 M = the new weak acid concentration is (1.0+0.1)/2 = 0.55 M. Therefore the new pH of the buffer is: pH = 4.76 + log(0.45M/0.55M) = 4.67 The difference is only 0.09 pH units! Compare that to adding 100 mL of 1.0 HCl to 2 L of water: Initial pH of water: 7.00 After addition of 0.1 mol of HCl, the concentration of H+ is 0.1/2 = 0.05 M The final pH is then -log(0.05M) = 1.30 The difference is a whopping 5.70 pH units!
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EzraA buffer regulates pH by resisting changes in the concentration of H+ ions. It contains a weak acid and its conjugate base, which can react with added acid or base to maintain a relatively stable pH. This allows the buffer solution to absorb excess H+ ions and prevent drastic changes in pH.
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Which solutions showed little or no change in pH why?
The solutions that showed little or no change in pH likely contained a buffer system. Buffer solutions resist changes in pH when small amounts of acid or base are added, as they can absorb or release protons to maintain pH stability. Typically, buffer systems consist of a weak acid and its conjugate base, or a weak base and its conjugate acid, to help regulate pH fluctuations.
Is Borax a acid or alkali?
Borax is an alkali, specifically a salt of boric acid. It has a basic pH value and can act as a buffer solution to help regulate pH levels in various applications.
Does a buffer always hold the pH of a solution at pH 7?
No, a buffer does not always hold the pH of a solution at pH 7. A buffer is a solution that can resist changes in pH when an acid or base is added. The actual pH at which a buffer solution can effectively resist changes depends on the specific components and their concentrations in the buffer system.
What is the purpose of a buffer and what does it do in a system?
A buffer is used in a system to help regulate and stabilize the pH level, or acidity, of a solution. It works by resisting changes in pH when an acid or base is added to the solution, helping to maintain a relatively constant pH level. This is important in various biological and chemical processes where maintaining a specific pH range is crucial for proper functioning.
How do you calibrate a pH meter?
To calibrate a pH meter, you typically use buffer solutions with known pH values (pH 4.01, pH 7.00, and pH 10.00 for example). Dip the pH meter probe into each buffer solution and adjust the meter readings to match the known pH values. Repeat this process for each buffer solution to ensure accurate calibration.
