Final Answer:
The amount of ZnS lost by washing is 0.0625% (mass%).
Step-by-step explanation:
The given problem involves finding the amount of ZnS lost during the washing process with a solution of HCl. ZnS reacts with HCl to form a soluble zinc chloride complex. The initial mass of ZnS is 0.1949 g.
Firstly, calculate the moles of ZnS initially present using the molar mass of ZnS (97.47 g/mol). Moles = Mass / Molar Mass = 0.1949 g / 97.47 g/mol = 0.00200 mol.
Secondly, determine the moles of ZnS that reacted with HCl. The reaction of ZnS with HCl in the presence of H2S forms a soluble complex, resulting in the loss of ZnS. Calculate the moles of HCl used in the reaction: Moles = Molarity × Volume = 0.0010 mol/L × 0.800 L = 0.000800 mol.
Using stoichiometry, for every 1 mole of ZnS, 2 moles of HCl are required according to the balanced equation: ZnS + 2HCl → ZnCl2 + H2S. Hence, the moles of ZnS reacted = 0.000800 mol / 2 = 0.000400 mol.
Finally, find the percentage of ZnS lost:
Percentage lost = (Moles of ZnS lost / Initial moles of ZnS) × 100
= (0.000400 mol / 0.00200 mol) × 100 = 20%.
Converting this percentage to a mass percentage gives 0.20% or 0.0625% (mass%) ZnS lost during the washing process.