Question

question 7
20 pts
a student was performing a spectrophotometric analysis of a colored compound. their data is given in the table below and in the corresponding graph. choose the appropriate axes titles, units, and sig figs. hint: think about what variable is under the experimenters control in this lab.
absorbance molar concentration
0.062 4.0×10^(-4)
0.126 8.0×10^(-4)
0.183 1.2×10^(-3)
0.459 2.9×10^(-3)
0.631 4.1×10^(-3)
y = 154.96x + 0.0009
r² = 0.9995
y - axis title: | select |

Explanation:

Step1: Identify independent variable

The experimenter controls the molar - concentration of the colored compound. So, molar concentration is the independent variable and usually goes on the x - axis. Absorbance is the dependent variable and goes on the y - axis.

Step2: Determine units

The units of molar concentration are moles per liter ($mol/L$ or $M$), and absorbance is a unit - less quantity as it is the ratio of the intensity of incident light to the intensity of transmitted light.

Step3: Consider significant figures

The molar concentration values are given to 2 significant figures in scientific notation, and the absorbance values are given to 3 significant figures.

Answer:

y - axis title: Absorbance (unit - less, 3 sig figs)
x - axis title: Molar Concentration ($mol/L$, 2 sig figs)