Question

Which of the following statements most accurately describes the physical properties of long
alkyl chains?
a. Long alkyl chains are non-polar and hydrophobic. They readily dissolve in water and
hexane. When close-packed the chains are held together by permanent dipole interactions.
b. Long alkyl chains are polar and hydrophilic. They readily dissolve in water but not
hexane. When close-packed the chains are held together by permanent dipole interactions.
c. Long alkyl chains are non-polar and hydrophobic. They readily dissolve in hexane but
not in water. When close-packed the chains are held together by ionic interactions.
d. Long alkyl chains are non-polar and hydrophobic. They readily dissolve in hexane but
not in water. When close-packed the chains are held together by transient dipole
interactions.
e. Long alkyl chains are polar and hydrophobic. They readily dissolve in hexane but not
water. When close-packed the chains are held together by transient dipole interactions.

Answer 1

Answer on Question #82106, Chemistry/ General Chemistry

a core ring with diameter 0f 4cm and a height of 5cm, the weight of the core ring with the undisturbed soil is 120g. the weight of the core ring with soil after oven drying for 24 hours is 105g. the volume occupied by air (Va)in the undisturbed soil sample is 16cm3. taking a particle density of the soil to be 2.65g/cm3, calculate the bulk density

Solution

The soil bulk density (BD), also known as dry bulk density, is the weight of dry soil ( $M_{\text{solids}}$ ) divided by the total soil volume ( $V_{\text{soil}}$ ). The total soil volume is the combined volume of solids and pores which may contain air ( $V_{\text{air}}$ ) or water ( $V_{\text{water}}$ ), or both.

Find the volume of core ring

$$V_{\text{soil}} = V_{\text{core ring}} = \pi r^2 \times h = \pi (d/2)^2 \times h = 3.14 \times (4/2)^2 \times 5 = 62.8 \text{ cm}^3$$ $$BD = M_{\text{solids}} / V_{\text{soil}} = 105 \text{ g} / 62.8 \text{ cm}^3 = 1.67 \text{ g/cm}^3$$

Answer: 1.67 g/cm³

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