NaC3H5O3 is needed to create 1000mL volume of ringers lactate with 6.5 ph
To determine the amount of NaC3H5O3 (sodium lactate) needed to create a 1000 mL volume of Ringer's lactate with a pH of 6.5, we need to follow a few steps:
Step 1: Understand the components of Ringer's lactate solution.
Ringer's lactate is a solution commonly used for intravenous administration to replenish electrolytes and fluid loss. It usually consists of various components, including sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2), sodium lactate (NaC3H5O3), and dextrose.
Step 2: Determine the pH adjustment.
To achieve a pH of 6.5, we need to adjust the concentration of sodium lactate. Sodium lactate is a weak base, and when dissolved in water, it dissociates into lactate ions (C3H5O3-) and sodium ions (Na+).
Step 3: Consider the dissociation of sodium lactate.
The pH of a solution is determined by the concentration of hydrogen ions (H+) present. In this case, the lactate ions (C3H5O3-) act as a weak base and can accept hydrogen ions, reducing the overall pH. By increasing the concentration of lactate ions, we can lower the pH of the solution.
Step 4: Calculation.
To calculate the amount of sodium lactate needed, we should note that the molecular weight of NaC3H5O3 is 112.06 g/mol.
Given that the required volume of the solution is 1000 mL and the final pH should be 6.5, we need to determine the concentration of sodium lactate required.
Step 5: Determine the concentration of sodium lactate.
The concentration can be calculated using the Henderson-Hasselbalch equation:
pH = pKa + log ([A-]/[HA])
In this case, A- represents the concentration of lactate ions, and HA represents the concentration of undissociated sodium lactate.
Given that lactate ions (C3H5O3-) are a weak base, they react with H+ ions to form undissociated sodium lactate (NaC3H5O3), which is the weak acid form. The pKa of lactate is approximately 3.86.
Therefore:
6.5 = 3.86 + log ([A-]/[HA])
Step 6: Solve for [A-]/[HA].
Rearranging the equation, we get:
[A-]/[HA] = 10^(6.5 - 3.86)
[A-]/[HA] = 3.73
Step 7: Calculate the concentration of sodium lactate.
To achieve a total volume of 1000 mL, we need to consider the desired concentration of lactate ions (A-).
Let x represent the desired concentration of lactate ions (A-). Consequently, the concentration of undissociated sodium lactate (HA) would be (3.73 - x).
By multiplying the concentration (x) and the molecular weight (112.06 g/mol), we can obtain the weight (W) of sodium lactate needed:
W = (x * 112.06) + [(3.73 - x) * 112.06]
Step 8: Calculate the weight of sodium lactate needed.
Substituting the desired concentration of lactate ions (x) with its appropriate value (let's say 1.5):
W = (1.5 * 112.06) + [(3.73 - 1.5) * 112.06]
W = 168.09 + (2.23 * 112.06)
W = 168.09 + 249.39
W ≈ 417.48 g
Therefore, approximately 417.48 grams of NaC3H5O3 (sodium lactate) are required to create a 1000 mL volume of Ringer's lactate solution with a pH of 6.5.