Question

Select the correct answer.

Thomas has 235 grams of K2S in the chemistry lab. How many atoms of potassium (K) are in 235 grams of the compound?

A.
2.13 × 1023
B.
4.26 × 1023
C.
2.57 × 1024
D.
3.37 × 1024
E.
7.08 × 1024

Answer 1

Answer:

c) 2.57 × 10^24

Explanation:

Given,

Thomas has 235 grams of K2S in the chemistry lab.

First let us find the molar mass of K2S:

M = 2(39) + 1(32)

M = 78 + 32

M = 110 g

No.of moles = Given mass/molar mass

No.of moles = 235/110 = 2.13 moles

» I mole of any substance contain 6.022×10^23 particles

» 2.13 moles of K2S contains 2.13×6.022×10^23 K2S molecules.

1 molecules of K2S contains 2 'K' atoms

» 2.13 moles of K2S contains 2×2.13×6.022×10^23 potassium atoms

= 2.567 × 10^24 atoms of K

= 2.57 × 10^24 atoms of K

Answer 2

Answer:

c

Explanation:

2.57 x 10^24

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