Question
(Adapled from Density of Aqueous Naci solutions by Roos Nord and slephen E. Schumery. ern Michigan Uni Objectives of a swhstance, exrensive properties associated wirh a specific s of subsramoe To learn how to measure auss and voinwe orohsecrs To learn how to calculate densiy fuw Introduction Density is an important property bstance. The density can be found using the equation love The densiry liquid can directly emfation of the solution this we will be measuring the density of some sodium chloride solutious For a liquid, volume is determined using graduated glassware It is also important to record the emperature because density is temperature dependent, Inthis experiment, temperature should be held Concentration of an aqueous solution will be expressed in mass percentage using the following The density of squeous NaCl solutions is a nearly linear function of the concentration in mass percent, so a standard curve can be constructed. In this case, we will be plotting density (y value) vs. mass NaCI(x-value), and a best fit line will be drawn using Excel (which can be downloaded through the University of Memphis website). Using the line that is made, we can use the equation of the line y-mxtb) to find the concentration of the unknown. Preparing the Standard Curve Prepare the five standard solutions shown in the table by following steps 1-8 to prepare each solution. Mass of Naci olution Numbe
Explanation / Answer
Density measurement
1) The graph demonstretes the relationship between the density of the material with its concentration in mass%.
The relation found was linear.
2)
a) density = mass/volume
= 116.52 g/(21.7 - 8.6) ml
= 8.9 g/ml
The density matches with the literature density value for Cobalt. Hence the matel in consideration is cobalt (Co)
b) Extrinsic property is one that depends upon the surrounding and is not a constant for a substance like mass of an object varies depending upon the type. Density is an intrinsic property in the sense that, it remains as a constant for a given substance.
c) volume after adding metal = (58.26/8.9) + 8.6
= 15.146 ml
3) Copper is denser than zinc, so If the penny is heavier, it is from old stock and If it is lighter it is made of zinc and is thus from the new stock.
