Question

What is the mass, in grams, of 9.10 x 1024 molecules of methanol (CH3OH) ? mass:

Answer 1

1)

use:

number of mol = number of molecules / Avogadro’s number

number of mol = 9.1*10^24 / 6.022*10^23 mol

number of mol = 15.11 mol

Molar mass of CH3OH,

MM = 1*MM(C) + 4*MM(H) + 1*MM(O)

= 1*12.01 + 4*1.008 + 1*16.0

= 32.042 g/mol

use:

mass of CH3OH,

m = number of mol * molar mass

= 15.11 mol * 32.04 g/mol

= 4.842*10^2 g

Answer: 484 g

2)

a)

Molar mass of As = 74.92 g/mol

So, mass of 1 mol = 74.92 g

Answer: 74.92 g

b)

Molar mass of B = 10.81 g/mol

So, mass of 1 mol = 10.81 g

Answer: 10.81 g

C)

Molar mass of Ge = 72.63 g/mol

So, mass of 1 mol = 72.63 g

Answer: 72.63 g

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