Question

Ethanol is the substance commonly called alcohol. The density of ethanol 0.8g/ml. at 293 K. if 1.2 moles of ethanol is required for a particular experiment, what volume of ethanol should be measured out?
A. ${\text{55}}{\text{.2 ml}}$
B.${\text{57}}{\text{.5 ml}}$
C. ${\text{69 ml}}$
D. \[{\text{47}}{\text{.9 ml}}\]

Answer 1

Hint:
Density: Density is a measure of mass per unit of volume. The average density of an object equals its total mass divided by its total volume. An object made from a comparatively dense material (such as iron) will have less volume than an object of equal mass made from some less dense substance (such as water).
\[{\text{Density = }}\dfrac{{{\text{mass}}}}{{{\text{volume}}}}\]
Number of moles is measured by ${\text{n = }}\dfrac{{\text{Weight}}}{{{\text{Gram Molecular Weight}}}}$

Complete step by step solution:
${\text{number}}\,{\text{of}}\,{\text{moles = }}\dfrac{{{\text{weight}}}}{{{\text{gram}}\,{\text{molecular}}\,{\text{weight}}}}$
$
  \Rightarrow {\text{1}}{\text{.2 = }}\dfrac{{\text{w}}}{{{\text{46}}}} \\
  \Rightarrow {\text{Mass = 1}}{\text{.2}} \times {\text{46}} = 55{\text{.2gms}} \\
 $
\[{\text{Density = }}\dfrac{{{\text{mass}}}}{{{\text{volume}}}}\]
$ \Rightarrow {\text{volume = }}\dfrac{{{\text{mass}}}}{{{\text{density}}}}{\text{ = }}\dfrac{{{\text{55}}{\text{.2}}}}{{{\text{0}}{\text{.8}}}}$
$ \Rightarrow {\text{Volume = 69 ml}}$

Hence, option “C” is correct

Note:
Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied. An object's mass also determines the strength of its gravitational attraction to other bodies
Volume is the quantity of three-dimensional space enclosed by a closed surface, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains.[1] Volume is often quantified numerically using the SI derived unit, the cubic metre