Question

what is the mass in grams of 6.023*10^23 atoms of calcium

Answer 1

Explanation:

How does this help you? Well, it happens that

N

A

,

Avogadro's Number

≅

6.022

×

10

23

⋅

m

o

l

−

1

.

And it is stated on your trusty Periodic Table that the molar mass of

C

a

is

40.08

⋅

g

⋅

m

o

l

−

1

. So, if we specify a molar quantity, we specify a precise number of atoms and molecules that can be approximated by mass.

Answer 2

$\huge \text{\underline {ANSWER}}$

Mass of 6.023 * 10²³ atoms of Ca = 40g

$\huge \text{\underline {EXPLANATION}}$

We know that,

Number of moles = Number of atoms / Avogadro number

Number of moles = Given mass / Atomic mass

Hence,

Number of atoms / Avogadro number = Given mass / Atomic mass

or

Given mass = (Number of atoms / Avogadro number) * Atomic mas

In the given question,

Number of atoms = 6.023 * 10²³

Avogadro number = 6.023 * 10²³

Atomic mass of calcium = 40g

Substituting all these values in we get,

Given mass = (6.023 * 10²³ / 6.023 * 10²³)  *  40

Given mass = 40g