CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
When hydrogen sulfide gas dissolves in water, it can undergo two successive deprotonation steps in the presence of hydroxide ions. The overall process can be represented by the sequence below.
Step 1: H2S(aq)+OH−(aq)→HS−(aq)+H2O(l)
Step 2: HS−(aq)+OH−(aq)→S2−(aq)+H2O(l)
Answer the following questions about this two-step process.
(a) For Step 1, identify the conjugate acid–base pair created by the proton transfer.
(b) For Step 2, identify the conjugate acid–base pair created by the proton transfer.
(c) Write the net ionic equation obtained by adding Step 1 and Step 2, and list every distinct conjugate acid–base pair that appears in the overall reaction sequence.
(d) Explain how the presence of two acidic protons in H2S is reflected in the sequence of conjugate pairs you identified.