Multiple Choice
Which of the following substances is compatible with both water and oil, acting as an emulsifier?
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6. Chemical Quantities & Aqueous Reactions
Solubility Rules
Multiple Choice
Which of the following correctly describes the dissolution of potassium sulfide (K2S) in water?
A
K2S is insoluble in water because sulfide salts are generally insoluble.
B
K2S is soluble in water because all potassium salts are soluble.
C
K2S partially dissolves in water, forming a precipitate.
D
K2S reacts with water to form potassium hydroxide and hydrogen sulfide gas.
Verified step by step guidance1
Step 1: Understand the solubility rules for ionic compounds in water. Generally, all potassium (K⁺) salts are soluble in water regardless of the anion they are paired with.
Step 2: Recognize that potassium sulfide (K₂S) is an ionic compound composed of potassium ions (K⁺) and sulfide ions (S²⁻). Since potassium salts are soluble, K₂S should dissolve in water.
Step 3: Consider the behavior of the sulfide ion (S²⁻) in water. Sulfide ions can react with water to some extent, producing hydroxide ions (OH⁻) and hydrogen sulfide (H₂S) gas, but this is a secondary reaction and does not prevent the initial dissolution.
Step 4: Evaluate the options given: the statement that K₂S is insoluble is incorrect based on solubility rules; partial dissolution with precipitate formation is unlikely; and while K₂S can react with water, the primary description of dissolution focuses on solubility.
Step 5: Conclude that the best description is that K₂S is soluble in water because all potassium salts are soluble, which aligns with standard solubility rules.
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