Exothermic Reaction Accelerates Due to Rising Temperature

Steps:

• Exothermic reaction releases heat, raising the mixture's temperature since it's uncontrolled.
• Higher temperature increases the reaction rate constant per Arrhenius equation.
• Faster rate causes reactant concentration to drop more quickly over time.
• Graph shows initial slow decrease accelerating to steeper decline.

Why B is correct:

• B depicts a curve with increasingly negative slope, matching accelerated rate from temperature rise (Arrhenius: k = A e^(-Ea/RT), where rising T boosts k).

Why the others are wrong:

• A: Linear decrease implies constant rate, ignoring temperature effect.
• C: Exponential decay suggests fixed rate, not acceleration.
• D: Concave up curve indicates slowing rate, opposite of heating.

Final answer: B