A Gran plot (also known as Gran titration or the Gran method) is a common means of standardizing a titrate or titrant by estimating the equivalence volume or end point in a strong acid-strong base titration or in a potentiometric titration.
How does a Gran plot work?
Gran’s plotting is a method of end point detection that uses a linear decrease in the millimoles of chloride in the region well before the end point of the titration curve (Frontside Gran’s). If the correct region is found, extrapolation to zero millimoles of chloride will intersect the volume axis at the end point.
What is the slope of a Gran plot?
A plot of Vb 10-pH versus Vb is called a Gran plot. If γHA/γA- is constant, such a plot is a. straight line with a slope of -Ka γHA/γA-. When y (Vb 10-pH) equals zero, Vb = Ve so the. x-intercept is the equivalence point volume.
What does the titration curve tell you?
A titration curve is a plot showing the change in pH of the solution in the conical flask as the reagent is added from the burette.
What is Gran alkalinity?
Gran alkalinity method is a more accurate technique used explicitly for low level alkalinity samples. It is performed on samples with a pH less than 7.0. Method Summary. The alkalinity titration is carried well past the total inflection point to about pH 3.0.
What indicator is best for titration?
phenolphthalein
The indicator phenolphthalein, whose range spans from pH 8 to 10, therefore makes a good choice for this type of titration. If you don’t know the pH change around the equivalence point of your titration, consult a general chemistry textbook.
Why are titration curves S shaped?
The titration of either a strong acid with a strong base or a strong base with a strong acid produces an S-shaped curve. Due to the leveling effect, the shape of the curve for a titration involving a strong acid and a strong base depends on only the concentrations of the acid and base, not their identities.
How does titration determine alkalinity?
The total alkalinity analysis involves titration. In this test, titration is the addition of small, precise quantities of sulfuric acid (the reagent) to the sample until the sample reaches a certain pH (known as an endpoint). Th e amount of acid used corresponds to the total alkalinity of the sample.
How does titration determine the alkalinity of water?
Alkalinity is determined by titrating a water sample with a strong acid (such as chlorine and sulfuric acid) and expressed by the calcium carbonate content (mg/L) corresponding to the amount of acid consumed until the pH value reaches the prescribed value. Alkalinity measured with the end point of pH4.
What happens if you use the wrong indicator in a titration?
In contrast, using the wrong indicator for a titration of a weak acid or a weak base can result in relatively large errors, as illustrated in Figure 17.3. 3.
