Question

What is the mass, in grams, of 1.00x1024 atoms Mn? a. 92.0 g Mn c. 91.3 g Mn b. 91.0 g Mn d. 91.5 g Mn Please select the best answer from the choices provided A B C D

Answer 1

(1.00*10²⁴ atoms)*1 mol/(6.02*10²³ atoms)=

10²⁴/6.02*10²³ mol = 1.661 mol Mn

M(Mn)=54.9 g/mol

1.661 mol Mn*54.9 g/1 mol=91.2 g

Answer: 91.3 g

Answer 2

Answer:

The correct option is c

Explanation:

The formula to use here is

n = m ÷ m.m

where is n = number of moles

m = mass of the substance (Mn)

m.m = molar mass (of Mn)

The number of moles was not given but can be calculated from the value given (the number of particles/atoms).

Number of atoms = number of moles (n) × avogadro's constant

Hence n = Number of atoms ÷ avogadro's constant  

Avogadro's constant = 6.02 × 10²³ mol⁻¹

Number of atoms = 1.00 ₓ 10²⁴

n = 1.00 ₓ 10²⁴ ÷ 6.02 × 10²³

n = 1.66 moles

Recall n = m ÷ m.m

∴ m = n × m.m

molar mass of Manganese (Mn) = 55 g/mol

m = 1.66 × 55

m = 91.3 g (option c)