Question

1. The mass of a density bottle is 45 g when empty, 55g when filled with water, and 75 g when filled
with alcohol. Find density of alcohol​

Answer 1

Mass of empty bottle, mb = 25.25 g

When bottle is filled with water, the mass of bottle is, mbw = 55.75 g

Thus, mass of water, mw = 55.75 - 25.25 g = 30.5 g

When filled with alcohol, mass of the bottle is, mba = 45.50 g

Thus, mass of alcohol, ma = 45.50 - 25.25 = 20.25 g

Volume of bottle = volume occupied by water

We know,

density = mass/ volume

density of water = 1 g/cm3

mass of water = 30.5 g

Thus, volume of water, vw = mw / 1 = 30.5 cm3

Hence,

volume of bottle = 30.5 cm3

volume occupied by water = voulme occupied by alcohol = 30.5 cm3

R e l a t i v e space d e n s i t y space o f space a l c o h o l space equals fraction numerator d e n s i t y space o f space a l c o h o l over denominator d e n s i t y space o f space w a t e r end fraction equals fraction numerator begin display style bevelled fraction numerator m a s s space o f space a l c o h o l space over denominator v o l u m e space o f space a l c o h o l end fraction end style over denominator begin display style bevelled fraction numerator m a s s space o f space w a t e r over denominator v o l u m e space o f space w a t e r end fraction end style end fraction space equals space fraction numerator m a s s space o f space a l c o h o l over denominator m a s s space o f space w a t e r end fraction

equals space m subscript a over m subscript w space... space left parenthesis because v subscript w equals space v subscript a right parenthesis

equals space fraction numerator 20.25 over denominator 30.5 end fraction space equals space 0.663 space almost equal to space 0.7

density of alcohol = mass of alcohol/ volume of alcohol = 20.25/30.5 = 0.66 g/cm3 = 0.7 g/cm3