When a mixture of sulfur and metallic silver is heated, silver sulfide is produced. What mass of silver sulfide is produced from a mixture of 3.0 g Ag and 3.0 g S8?
16 Ag(s) + S8(s) > 8Ag2S(s)
This is a limiting reagent problem. Here is a worked example.
http://www.jiskha.com/science/chemistry/limiting_reagent_problem.html
To find the mass of silver sulfide produced, we need to determine the limiting reactant between silver (Ag) and sulfur (S8). The limiting reactant is the one that is completely consumed and determines the maximum amount of product that can be formed.
To find the limiting reactant, we need to compare the number of moles of Ag and S8. We can use the molar mass of each element to convert the given masses to moles.
First, calculate the number of moles of Ag:
Molar mass of Ag = 107.87 g/mol
Number of moles of Ag = Mass of Ag / Molar mass of Ag
= 3.0 g / 107.87 g/mol
≈ 0.028 moles of Ag
Next, calculate the number of moles of S8:
Molar mass of S8 = 32.07 g/mol (the sulfur molecule contains 8 S atoms)
Number of moles of S8 = Mass of S8 / Molar mass of S8
= 3.0 g / 32.07 g/mol
≈ 0.094 moles of S8
Now, we can look at the balanced chemical equation:
16 Ag(s) + S8(s) > 8Ag2S(s)
According to the balanced equation, 16 moles of Ag react with 1 mole of S8 to produce 8 moles of Ag2S.
Comparing the moles of Ag and S8, we can see that we need 16 moles of Ag for every 1 mole of S8. However, we only have 0.028 moles of Ag and 0.094 moles of S8.
Since Ag is the limiting reactant (it is less than the stoichiometric ratio), we can use it to determine the maximum amount of Ag2S that can be formed.
Using the stoichiometric ratio, we find that 16 moles of Ag produces 8 moles of Ag2S. Therefore, 0.028 moles of Ag will produce (8/16) × 0.028 = 0.014 moles of Ag2S.
Finally, we can find the mass of Ag2S using its molar mass:
Molar mass of Ag2S = 247.8 g/mol (2 moles of Ag + 1 mole of S)
Mass of Ag2S = Number of moles of Ag2S × Molar mass of Ag2S
= 0.014 moles × 247.8 g/mol
≈ 3.47 g
Therefore, approximately 3.47 grams of silver sulfide (Ag2S) is produced from the given mixture of 3.0 g Ag and 3.0 g S8.