Final answer:
The student should measure out approximately 57 cm³ of diethylamine to obtain 40.0 g, based on the given density of 0.706 g/cm³.
Step-by-step explanation:
To calculate the volume of diethylamine the student should pour out, we use the density formula:
Density (D) = mass (m) / volume (V)
To find the volume (V), we rearrange the formula:
V = m / D
Given that the mass (m) of diethylamine needed is 40.0 g and the density (D) is 0.706 g/cm³, we can calculate the volume (V) as follows:
V = 40.0 g / 0.706 g/cm³
V ≈ 56.66 cm³
Since the calculation is based on two significant figures for the density, the volume should also be reported with two significant figures:
V = 57 cm³ of diethylamine