Problem: Consider the following titration curves for two weak acids (see the figures), both titrated with 0.100 M NaOH., Which of the two acid solutions is more concentrated?

FREE Expert Solution

Weak acid and strong base titration

  • pH gradually increases as it approaches the equivalence point
  • pH at the equivalence point is more than 7.00

The steepest point in the curve will be the equivalence point. 

  • This is basically the turning point in the curve. 
  • This is usually the middle point of the horizontal segment.


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Problem Details

Consider the following titration curves for two weak acids (see the figures), both titrated with 0.100 M NaOH.,

The figure labeled (a) shows pH as a function of volume of base added. The pH is measured from 0 to 14 on the y-axis, while the volume of base added is measured from 0 to 100 milliliters on the x-axis. The curve of the plot goes up gradually from pH 4.3 at 0 milliliters to pH 8.2 at 37 milliliters, next the plot goes up steeply to pH 11.8 at 39 milliliters, and finally the plot goes up gradually to pH 12.2 at 100 milliliters.

 The figure labeled (b) shows pH as a function of volume of base added. The pH is measured from 0 to 14 on the y-axis, while the volume of base added is measured from 0 to 100 milliliters on the x-axis. The curve of the plot goes up gradually from pH 3.0 at 0 milliliters to pH 6.2 at 29 milliliters, next the plot goes up steeply to pH 11.8 at 31 milliliters, and finally the plot goes up gradually to pH 12.2 at 100 milliliters.

Which of the two acid solutions is more concentrated?

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