Find the density of an unknown liquid in a beaker. The empty beaker's mass is 165
grams. With the unknown liquid inside the beaker, the total mass is 309 grams. The
volume of the unknown liquid is 125mL. Is the liquid pure water? Explain your answer.

Density = mass / volumeSo in order calculate the density of the unknown liquid, we need to knowits mass and its volume.If the mass of the beaker is  165 grams  empty and  309 grams with something in it, then the mass of the stuff in it must be(309 - 165) = 144 grams.The question tells us that its volume is  125 mL  (same as 125 cm³),so we have everything we need.Density = mass/volume = 144/125 = 1.152 grams per cm³ .The density of pure water is  1.000 gram per cm³ , so the unknown liquid is definitely not pure water.The density of this unknown liquid is  15.2%  more than that of pure water.Even if water had a huge amount of pollution and junk in it, its density would probably not be that much greater than 1.000 .  So the unknown liquid is probably not polluted water either.

Density is defined as mass divided by volume.  SO we have to find the mass of unknown liquid first and then divide by its volume.Mass of the liquid =  total mass of beaker and liquid inside the beaker -                                                                                          mass of empty beaker               = 309 grams - 165 grams                 = 144 gramsvolume of unknown liquid = 125 ml    givenDensity =  mass / volume  =  144 / 125  = 1.152 gm / ml