# Anthracene, a hydrocarbon obtained from coal, has an empericalformula of C7H5. To find its molecularformula, you dissolve 0.500g in 30.0g of benzene. The boilingpoint of pure benzene is 80.10 o C, whereas the solutionhas a boiling point of 80.34 oC . What is the molecularformula of anthracene?

Question
Other
Anthracene, a hydrocarbon obtained from coal, has an empericalformula of C7H5. To find its molecularformula, you dissolve 0.500g in 30.0g of benzene. The boilingpoint of pure benzene is 80.10 o C, whereas the solutionhas a boiling point of 80.34 oC . What is the molecularformula of anthracene?

2021-02-01
?Tb= Kbm; Kb= 2.53oC/m for benzene m =?Tb/Kb $$\displaystyle={\frac{{{\left({80.34}{o}{C}-{80.10}{o}{C}\right)}}}{{{\left({2.53}{o}\frac{{C}}{{m}}\right)}}}}={0.095}{m}={0.095}$$ moles anthracene/1000 g solvent
moles of anthracene = (0.095 moles/1000g benzene)(30.0g benzene) 2.85\times 10-3moles
MW anthracene = $$\displaystyle{\frac{{{0.500}{g}}}{{{2.85}\times{10}-{3}{m}{o}\le{s}}}}$$ = 175.44g/mole
whole number to multiply subscripts in empirical formula =175.44/empirical formula weight anthracene = $$\displaystyle{\frac{{{175.44}}}{{{89}}}}$$ = 1.97 =2
Molecular formula of anthracene is C14H10

### Relevant Questions

The bulk density of soil is defined as the mass of dry solidsper unit bulk volume. A high bulk density implies a compact soilwith few pores. Bulk density is an important factor in influencing root development, seedling emergence, and aeration. Let X denotethe bulk density of Pima clay loam. Studies show that X is normally distributed with $$\displaystyle\mu={1.5}$$ and $$\displaystyle\sigma={0.2}\frac{{g}}{{c}}{m}^{{3}}$$.
(a) What is thedensity for X? Sketch a graph of the density function. Indicate onthis graph the probability that X lies between 1.1 and 1.9. Findthis probability.
(b) Find the probability that arandomly selected sample of Pima clay loam will have bulk densityless than $$\displaystyle{0.9}\frac{{g}}{{c}}{m}^{{3}}$$.
(c) Would you be surprised if a randomly selected sample of this type of soil has a bulkdensity in excess of $$\displaystyle{2.0}\frac{{g}}{{c}}{m}^{{3}}$$? Explain, based on theprobability of this occurring.
(d) What point has the property that only 10% of the soil samples have bulk density this high orhigher?
(e) What is the moment generating function for X?
A 0.30 kg ladle sliding on a horizontal frictionless surface isattached to one end of a horizontal spring (k = 500 N/m) whoseother end is fixed. The ladle has a kinetic energy of 10 J as itpasses through its equilibrium position (the point at which thespring force is zero).
(a) At what rate is the spring doing work on the ladle as the ladlepasses through its equilibrium position?
(b) At what rate is the spring doing work on the ladle when thespring is compressed 0.10 m and the ladle is moving away from theequilibrium position?
The normal boiling point of benzene is 80 degrees celsius.What is the vapor pressure of benzene at 80 degress celsius?
Assume that a 1.00-kg ball is thrown solely by the action of the forearm, which rotates about the elbow joint under the action of the triceps muscle. The ball is accelerated uniformly from rest to 10.0 m/s in 0.350 s, at which point it is released. Calculate (a) the angular acceleration of the arm, and (b) the force required of the triceps muscle. Assume that the forearm has a mass of 3.70 kg and rotates like a uniform rod about an axis at its end.
A 2.0-kg projectile is fired with initial velocity components $$\displaystyle{v}_{{{0}{x}}}={30}$$ m/s and $$\displaystyle{v}_{{{0}{y}}}={40}$$ m/s from a point on the earth's surface. Neglect any effects due to air resistance. What is the kinetic energy of the projectile when it reaches the highest point in its trajectory? How much work was done in firing the projectile?
A 1004.0g sample of calcium carbonate that is 95.0% pure gives 225L of $$\displaystyle{C}{O}_{{{2}}}$$ at STP when reacted with an excess ofhydrochloric acid.
What is the density (in g/L) of the carbondioxide?
a)
b)
Figure shows a nonconducting rod with a uniformly distributed charge +Q. The rod forms a 10/22 of circle with radius R and produces an electric field of magnitude Earc at its center of curvature P. If the arc is collapsed to a point at distance R from P, by what factor is the magnitude of the electric field at P multiplied?
The dominant form of drag experienced by vehicles (bikes, cars,planes, etc.) at operating speeds is called form drag. Itincreases quadratically with velocity (essentially because theamount of air you run into increase with v and so does the amount of force you must exert on each small volume of air). Thus
$$\displaystyle{F}_{{{d}{r}{u}{g}}}={C}_{{d}}{A}{v}^{{2}}$$
where A is the cross-sectional area of the vehicle and $$\displaystyle{C}_{{d}}$$ is called the coefficient of drag.
Part A:
Consider a vehicle moving with constant velocity $$\displaystyle\vec{{{v}}}$$. Find the power dissipated by form drag.
Express your answer in terms of $$\displaystyle{C}_{{d}},{A},$$ and speed v.
Part B:
A certain car has an engine that provides a maximum power $$\displaystyle{P}_{{0}}$$. Suppose that the maximum speed of thee car, $$\displaystyle{v}_{{0}}$$, is limited by a drag force proportional to the square of the speed (as in the previous part). The car engine is now modified, so that the new power $$\displaystyle{P}_{{1}}$$ is 10 percent greater than the original power ($$\displaystyle{P}_{{1}}={110}\%{P}_{{0}}$$).
Assume the following:
The top speed is limited by air drag.
The magnitude of the force of air drag at these speeds is proportional to the square of the speed.
By what percentage, $$\displaystyle{\frac{{{v}_{{1}}-{v}_{{0}}}}{{{v}_{{0}}}}}$$, is the top speed of the car increased?
Express the percent increase in top speed numerically to two significant figures.
Consider a point charge with $$\displaystyle{q}={1.5}\times{10}^{{-{8}}}{C}$$.
The crane shown in the drawing is lifting a 182-kg crate upward with an acceleration of $$\displaystyle{1.5}\frac{{m}}{{s}^{{2}}}$$. The cable from the crate passes over a solid cylindrical pulley at the top of the boom. The pulley has a mass of 130 kg. The cable is then wound ontoa hollow cylindrical drum that is mounted on the deck of the crane.The mass of the drum is 150 kg, and its radius is 0.76 m. The engine applies a counter clockwise torque to the drum in order towind up the cable. What is the magnitude of this torque? Ignore the mass of the cable.