Question

Describe the purpose of a calibration curve and how one was used to find the concentration of phosphate in the unknown.

A) It relates concentration to a measurable property and was used to determine phosphate concentration by comparing absorbance values.
B) It measures the volume of a solution and was used to find the concentration of phosphate by titration.
C) It measures temperature changes and was used to determine phosphate concentration by calorimetry.
D) It determines the pH of a solution and was used to find the concentration of phosphate by pH titration.

Answer 1

A calibration curve relates concentration to a measurable property, such as absorbance, and was used to determine the concentration of phosphate by comparing the absorbance values of the unknown to the curve.

Step-by-step explanation:

The purpose of a calibration curve is to establish a relationship between a measurable property and the concentration of a substance. In the case of determining the concentration of phosphate in an unknown sample, the calibration curve would typically correlate the absorbance values obtained from a spectrophotometer to known concentrations of phosphate. By measuring the absorbance of the unknown sample and comparing it to the curve, one can determine the phosphate concentration.

Therefore, the correct answer to the question is A) It relates concentration to a measurable property and was used to determine phosphate concentration by comparing absorbance values. This is because a calibration curve in the context mentioned above would not measure volume, temperature, or pH but rather would use the absorbance measurements to determine the concentration of phosphate in the sample.