The density of solid W is 19.3 g/cm3. How many atoms are present per cubic centi
ID: 975675 • Letter: T
Question
The density of solid W is 19.3 g/cm3. How many atoms are present per cubic centimeter of W?
The density of solid W is 19.3 g/cm^3. How many atoms are present per cubic centimeter of W? Incorrect. To convert from grams to moles, use the molar mass of the metal. To convert from moles Ot atoms, use Avodadro's number. As a solid, W adopts a body-centered cubic unit cell How many unit cells are present per cubic centimeter of W? What is the volume of a unit cell of this metal? What is the edge length of a unit cell of W?Explanation / Answer
1) molar mass of W=183.84g/mol
So 19.3g contains # moles=19.3g/183.84g/mol=0.105 moles
No of atoms in 0.105 moles=6.022*10^23 atoms/mole*0.105mol=0.6322*10^23=6.322*10^22 atoms
Hence 6.322*10^22 atoms per cm^3
2)edge length=a
volume of unit cell=a^3
mass of each unit cell b.c.c having two atoms =density*volume=a^3*19.3g/cm3
but mass of two atoms of W=(183.84 g/mol )/(6.022*10^23 atoms/mol)=30.528*10^23 g/atom
a^3*19.3g/cm3= 2* 30.528*10^23 g/atom=mass of two atoms
a^3=2* 30.528*10^23/19.3 =3.163*10^23 cm3=0.3163*10^24 cm3
a=0.6813*10^8=6.813*10^7 (answer)