Blog 2: Unit Cell of NaCl

1 Unit Cell of NaCl

The model shown above measured 6cm in length, height and width.  It is 216cm^3.  An actual, theoretical NaCl cube with the exact make-up of the model above, would be 0.914nm in length and width.  It would then be only 0.764nm^3 in volume, or 0.0000000764cm^3.  The table below contains the height, width and length of the actual grain of salt viewed at a magnification of 50 times in nm, m, and angstroms.  

Table 1
NaCl Cube Dimensions (atomic dimensions)
	Height	Width	Length
nm	0.918nm	0.918nm	0.918nm
angstroms	9.81 Å	9.81Å	9.81Å
meters	0.981x10^-9m	0.981x10^-9m	0.981x10^-9m

Table 2
NaCl Salt Model Dimensions
Units	Height	Width	Length
nm	590000	590000	590000
angstroms	5900000	5900000	5900000
meters	0.00059	0.00059	0.00059

              

We discovered the actual length and width of the sample salt cube by using a ruler set next to the crystal, magnified 50 times, was roughly 0.59mm.  The volume of the sample cube was about 0.206mm^3. A theoretical unit cell of NaCl would be 0.918nm in length and width, for a volume of 0.764nm^3, as described in the NaCl FCC Dimensions table 2.  

The sample grain weighed 1.17x10^-4g.  The amount of atoms in the grain =[ (weight of sample grain)/(average amu between Na and Cl/Avogadro’s Number) ]=[ (1.17X10^-4)/(29.95g/mol)/(6.022x1-^23)] = 2.41x10^18 atoms. Moles of NaCl equals:  1.17x10^-4g/(29.95g/mol) = 3.91x10^-6 mol.

If we were to put as many of the actual 0.914x0.914x0.914 NaCl Cubes inside the model cube we made,  we would have 65,645,514.22 cubes.  According to the grain sample we weighed, we would be able to fit 645,514 theoretically calculated NaCl cubes inside the grain sample measured .