Chemical Process Fundamentals & Reactions Flashcards

What does Le Chatelier's Principle state about a chemical system at equilibrium?

Answer: The system will shift to counteract any stress applied to it

Le Chatelier's Principle states that if a stress (temperature, pressure, concentration change) is applied to an equilibrium system, it will shift to partially oppose that stress.

Which of the following best describes an exothermic chemical reaction?

Answer: A reaction that releases heat into the surroundings

An exothermic reaction releases energy (heat) into the surroundings, resulting in a negative enthalpy change (ΔH < 0).

What is the primary role of a catalyst in a chemical reaction?

Answer: It lowers the activation energy without being consumed

A catalyst lowers the activation energy of a reaction, speeding it up without being consumed or altering the equilibrium position.

In a process plant, pH is a measure of which property of an aqueous solution?

Answer: Hydrogen ion (H⁺) activity or acidity/basicity

pH measures the hydrogen ion (H⁺) activity in solution; values below 7 are acidic, above 7 are basic, and 7 is neutral.

Which statement correctly distinguishes a physical change from a chemical change?

Answer: Physical changes alter form or state without producing new substances

A physical change alters the form, size, or state of matter without creating new chemical substances, while a chemical change produces new substances.

What unit is most commonly used to express the rate of a chemical reaction in a process setting?

Answer: Moles per liter per second (mol/L·s)

Reaction rate is expressed as the change in concentration (moles per liter) per unit time (per second), giving mol/L·s.

When temperature increases in a reversible exothermic reaction, what shift in equilibrium is expected?

Answer: Equilibrium shifts toward the reactants

According to Le Chatelier's Principle, adding heat to an exothermic reaction shifts the equilibrium toward the reactants to absorb the excess energy.