Make a buffer solution with the following specification pH=5.5 Volume=2L total concentration=1M ...
a) Name the components?...
b) How many grams of each component would you use to make 2L of solution
To make a buffer solution with the given specifications, you need to choose components that will maintain the desired pH of 5.5 when small amounts of acid or base are added. A buffer solution usually consists of a weak acid and its conjugate base (or a weak base and its conjugate acid).
a) Naming the components:
In this case, we will select a weak acid and its conjugate base to create the buffer solution. Let us choose acetic acid (CH3COOH) as the weak acid and sodium acetate (CH3COONa) as its conjugate base.
b) Calculating the grams of each component:
To determine the number of grams of each component required to prepare the buffer solution, we need to consider the concentration of the buffer and the desired volume.
Given:
pH = 5.5
Volume = 2L
Total concentration = 1M
1. Calculating the moles needed for the desired concentration:
Molarity (M) is the number of moles of solute per liter of solution. Since the total concentration is 1M and the volume is 2L, the number of moles (n) can be calculated as follows:
n = Molarity * Volume
n = 1M * 2L
n = 2 moles
2. Calculating the moles of acetic acid:
We need to choose the acid-to-base ratio that best maintains the pH of the buffer solution. A commonly used ratio is 1:1.
Since the moles of sodium acetate will be the same as the moles of acetic acid, we need 2 moles of each component.
3. Converting moles to grams:
To convert from moles to grams, we need to know the molar mass (grams per mole) for each component.
The molar mass of acetic acid (CH3COOH) is:
12.01g/mol (C) + 1.01g/mol (H) + 12.01g/mol (C) + 15.999g/mol (O) + 1.01g/mol (H) = 60.05g/mol
The molar mass of sodium acetate (CH3COONa) is:
12.01g/mol (C) + 1.01g/mol (H) + 12.01g/mol (C) + 15.999g/mol (O) + 22.99g/mol (Na) = 82.03g/mol
To calculate the grams of each component:
Mass = Moles * Molar Mass
For acetic acid:
Mass = 2 moles * 60.05g/mol = 120.1g
For sodium acetate:
Mass = 2 moles * 82.03g/mol = 164.06g
Therefore, to make 2L of buffer solution with a pH of 5.5 and a total concentration of 1M, you would need approximately 120.1 grams of acetic acid (CH3COOH) and 164.06 grams of sodium acetate (CH3COONa).