How many molecules of ethanol (c2h5oh) (the alcohol in alcoholic beverages) are present in 155 ml of ethanol? the density of ethanol is 0.789 g/cm3?

First convert volume to mass:

mass = 0.789 g/mL * 155 mL = 122.295 g

Then convert mass to number of moles:

number of moles = 122.295 g * (1 mole / 46 g) = 2.66 moles

Using avogadros number, we get the molecules:

number of molecules = 2.66 moles * 6.022 x 10^23 molecules / mole = 1.6 x 10^24 molecules

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

so she was walking and she stepped on warm jeffy , uh uh uhh dadye i just pooped my pants