Question

1. (a) (i) Define specific gravity (SG). (ii) Why water at 4 °C is used as the reference substance in SG calculation? overflow spout beaker measuring cylinder The figure above shows a large beaker with an overflow spout and a measuring cylinder, used to measure density of an insoluble solid. When placed inside the beaker it solid 1 floats with half of its volume submerged, solid 2 is fully submerged , while solid 3 or sinks to the bottom. Explain how the density of each solid could be determined, assuming the masses are known.

Answer 1

Solution:-

(a) -(i)The specific gravity is the ratio between the density of an object, and a reference substance. The specific gravity can tell us, based on its value, if the object will sink or float in our reference substance. Usually our reference substance is water which always has a density of 1 gram per milliliter or 1 gram per cubic centimeter.The formula for specific gravity, given that the reference substance is water, is the density of the object divided by the density of the water. The specific gravity has no unit because the units of the numerator and the denominator are the same.

(ii)When calculating the specific gravity of solids and liquids, the standard of comparison is water at 4 degrees Celsius, because water has its maximum density at this temperature.

As the temperature of warm water decreases, the water molecules slow down and the density increases. At 4 °C, the clusters start forming. The molecules are still slowing down and coming closer together, but the formation of clusters makes the molecules be further apart. ... Thus, the density of water is a maximum at 4 °C.

(iii)
Date : Solution (ii) overflow spout Pleaswing cyllinder find amount let volume 11 li - V By Archiemede's principle we know that - (6) Btrayant force = Wt. of displaced Water This buoyant force gets balanced with gravity in each case. we can of displaced wath in measuring cyllinder. mass of each object = m for object B = mug (weight of displaced water) mg wo of water displecat of object » Vox fox g = Vw X w x g density of object dersity of water since, half Yoxlo - Xox fw Volume of wath is displaced - mw g T Weight + 2 fo= Iw 103

Page: Date : B = mwg For object - Again = mg = Mw g 7 Vox Poxo = Vw X Lw x 8 Vw = Vo. - Yoxfo Nox fo As object is tere - submerged. ed] > To=fw=to3 kg/omst For Object - Since, it is sink to bottom So, it's density in more than water. So > 103 Kg/m3 In this case, exact density cannot be Calculated.