Her father had knocked gently. "Mira? Everything okay?"
The number 9.04 haunted Mira.
She cracked her knuckles. Then she cracked the exam open. hsc chemistry 9 crack
Compare Ka2 (1.02×10⁻⁷) to Kb (6.49×10⁻¹³). Ka2 is much larger . So the HSO₃⁻ acts as a weak acid. The solution is slightly acidic. Of course. The pH at equivalence is below 7. Not neutral. That was the trap. Her father had knocked gently
She flipped to the data sheet. Ka1 of H₂SO₃ = 1.54 × 10⁻². Ka2 = 1.02 × 10⁻⁷. Kb for HSO₃⁻ = Kw/Ka1 = (1×10⁻¹⁴)/(1.54×10⁻²) = 6.49×10⁻¹³. She cracked her knuckles
Mira put her head on the desk. The wood was cool. She could smell highlighter ink and her own exhausted sweat.
"You can't just will the answer," she whispered. That was her problem. She had spent the whole year trying to memorise chemistry like it was history. Dates. Formulas. But chemistry wasn't a list. It was a story. Protons moving. Electrons trading places. Water molecules huddling around ions like concerned neighbours.