1) How many sulfur atoms are there in 21.0 g of Al2S3? A) 8.42  1022 atoms D) 6.02  1023 atoms B) 2.53  1023 atoms E) 6.30  1026 atoms C) 2.14  1023 atoms Ans) B

In 21 grams of Al2S3 we have  2.53 *10^23 S atoms (optionB is correct)

Explanation:

Step 1: Data given

Mass of Al2S3 = 21.0 grams

Molar mass of Al2S3 = 150.158 g/mol

Number of Avogadro = 6.022 * 10^23 / moles

Step 2: Calculate moles of Al2S3

Moles Al2S3 = mass Al2S3 / molar mass Al2S3

Moles Al2S3 = 21.0 grams / 150.158 g/mol

Moles Al2S3 = 0.140 moles

Step 3: Calculate moles sulfur

For 1 mol Al2S3 we have 3 moles S

For 0.140 moles Al2S3 we have 3*0.140 = 0.420 moles S

Step 4: Calculate sulfur atoms

Number of sulfur atoms = moles * Number of Avogadro

Number of sulfur atoms = 0.420 moles * 6.022 * 10^23 / moles

Number of sulfur atoms = 2.53 *10^23 S atoms

In 21 grams of Al2S3 we have  2.53 *10^23 S atoms (optionB is correct)

if the concentration of products is decreased, the equilibrium will shift toward the products). add an inert gas (one that is not involved in the reaction) to the constant-volume reaction mixture: this will increase the total pressure of the system, but will have no effect on the equilibrium condition.

explanation:

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.