a buffer contains 0.010 mol of lactic acid and 0.050 mol of sodium lactate per liter . How do I find the molarity of the acid and base?
To find the molarity of the acid and base in the given buffer solution, you need to understand the concept of molarity and the dissociation of lactic acid.
Molarity is a measure of the concentration of a solute in a solution and is defined as the number of moles of solute per liter of solution. The formula to calculate molarity is:
Molarity (M) = Moles of Solute / Volume of Solution (in liters)
In the given buffer solution, lactic acid (C₃H₆O₃) and its conjugate base sodium lactate (C₃H₅O₃⁻) are present. Lactic acid partially dissociates in water to form lactate ions (C₃H₅O₃⁻) and hydrogen ions (H⁺) according to the equation:
C₃H₆O₃ ⇌ C₃H₅O₃⁻ + H⁺
Here, lactic acid acts as an acid, while sodium lactate acts as a base due to the presence of OH⁻ ions from the dissociated sodium hydroxide (NaOH).
Let's start by calculating the molarity of lactic acid (C₃H₆O₃):
Moles of lactic acid (C₃H₆O₃) = 0.010 mol (given)
Volume of solution = 1 liter (given)
Molarity of lactic acid (C₃H₆O₃) = Moles of lactic acid / Volume of solution
= 0.010 mol / 1 L
= 0.010 M
Therefore, the molarity of lactic acid is 0.010 M.
Next, let's calculate the molarity of the base (sodium lactate - C₃H₅O₃⁻):
Moles of sodium lactate (C₃H₅O₃⁻) = 0.050 mol (given)
Volume of solution = 1 liter (given)
Molarity of sodium lactate (C₃H₅O₃⁻) = Moles of sodium lactate / Volume of solution
= 0.050 mol / 1 L
= 0.050 M
Therefore, the molarity of the base (sodium lactate) is 0.050 M.
To summarize, the molarity of the lactic acid in the buffer solution is 0.010 M, while the molarity of the base (sodium lactate) is 0.050 M.