Question

4

What is the mass, in grams, of 5.20 x 1023 formula units of NaCl?
A 0.864 grams
11.2 grams
C 50.5 grams
D
304 grams

Answer 1

The mass of NaCl : 50.5 g

Further explanation

The mole is the number of particles(molecules, atoms, ions) contained in a substance

1 mol = 6.02.10²³ particles

Can be formulated

N=n x No

N = number of particles

n = mol

No = Avogadro's = 6.02.10²³

There are 5.20 x 10²³ units of NaCl, so mol NaCl :

`\tt n=(N)/(No)\\\\n=(5.2* 10^(23))/(6.02* 10^(23))\\\\n=0.864~moles`

Mass of NaCl(MW=71 g/mol) :

`\tt mass=mol* MW\\\\mass=0.864* 58.44\\\\mass=50.49\approx 50.5~g`