Physical chemistry

The half-life of a first-order reaction is calculated as ln(2)/k, making it dependent solely on the rate constant and entirely independent of the starting amount of reactant. Option A is incorrect because temperature directly influences the rate constant 'k' via the Arrhenius equation, which in turn alters the half-life.

HCl is a strong acid that fully dissociates in water, meaning a 0.01 M solution yields a hydrogen ion concentration of 10^-2 M. Since pH is defined as the negative logarithm of the hydrogen ion concentration, the pH is 2. Option A is incorrect because a pH of 1 would require a ten-fold higher concentration of 0.1 M HCl.

HCl is a strong acid that fully dissociates in water, meaning a 0.01 M solution yields a hydrogen ion concentration of 10^-2 M. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Option A is incorrect because a pH of 1 would require a ten-fold higher concentration of 0.1 M HCl.
• !Option A is incorrect because 0.5 moles would correspond to only 9 grams of water, representing an inversion of the division formula.
• !Option A is incorrect because temperature directly influences the rate constant 'k' via the Arrhenius equation, which in turn alters the half-life.

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