Question

Rank the following samples in number of atoms from least to greatest. a) 1.5 mol of K atoms b) 64 g of S c) 20 g of Be d) 25 g of Na

Answer 1

Answer:

Na < K < S < Be

Explanation:

Let's work with NA and molar mass of each.

- 1.5 mol of K → should be converted to atoms ( mol . NA)

1.5 mol . 6.02×10²³ = 9.03×10²³ atoms of K

- 64 g of S → should be converted to mol (mass / molar mass). Then, into atoms. (mol . NA)

64 g / 32.06 g/m = 1.99 mol

1.99 m . 6.02×10²³ = 1.20×10²⁴ atoms of S

- 20 g of Be → should be converted to mol (mass / molar mass). Then, into atoms. (mol . NA)

20 g / 9.01 g/m = 2.22 moles

2.22 m . 6.02×10²³ = 1.33×10²⁴ atoms of Be

- 25 g of Na → should be converted to mol (mass / molar mass). Then, into atoms. (mol . NA)

25 g / 23 g/m = 1.08 moles

1.08 m . 6.02×10²³ = 6.54×10²³ atoms of Na