10-4 Equilibrium

Which statement describes a reaction at equilibrium?

• The mass of the products must equal the mass of the reactants.

• The entropy of the reactants must equal the entropy of the products.

• The rate of formation of the products must equal the rate of formation of the reactants.

• The number of moles of the reactants must equal the number of moles of the products.

For a chemical system at equilibrium, the concentration of both the reactants and the products must

• decrease

• increase

• be constant

• be equal

Tags

NGSS.HS-PS1-6

Given the equation representing a system at equilibrium:

N₂O₄(g) ⇌ 2NO₂(g).

Which statement describes the concentration of the two gases in this system?

• The concentration of N₂O₄(g) must be less than the concentration of NO₂(g).

• The concentration of N₂O₄(g) must be greater than the concentration of NO₂(g).

• The concentration of N₂O₄(g) and the concentration of NO₂(g) must be equal.

• The concentration of N₂O₄(g) and the concentration of NO₂(g) must be constant.

Tags

NGSS.HS-PS1-7

Equilibrium can be reached by

• physical changes, only

• nuclear changes, only

• both physical changes and chemical changes

• both nuclear changes and chemical changes

When a reversible reaction is at equilibrium, the concentration of products and the concentration of reactants must be

• decreasing

• increasing

• constant

• equal

Tags

NGSS.HS-PS1-6

What occurs when a reaction reaches equilibrium?

• The concentration of the reactants increases.

• The concentration of the products increases.

• The rate of the forward reaction is equal to the rate of the reverse reaction.

• The rate of the forward reaction is slower than the rate of the reverse reaction.

Tags

NGSS.HS-PS1-6

A reaction reaches equilibrium at 100°C. The equation and graph representing this reaction are shown below.

N₂O₄(g) ⇌ NO₂(g).

The graph shows that the reaction is at equilibrium after 60 seconds because the concentrations of both NO₂(g) and N₂O₄(g) are .

• increasing

• decreasing

• constant

• zero

Which type of equilibrium exists in a sealed flask containing Br₂(l) and Br₂(g) at 298 K and 1.0 atm?

• static phase equilibrium

• static solution equilibrium

• dynamic phase equilibrium

• dynamic solution equilibrium

An open flask is half filled with water at 25°C. Phase equilibrium can be reached after _______.

• more water is added to the flask

• the flask is stoppered

• the temperature is decreased to 15°C

• the temperature is increased to 35°C

Tags

NGSS.HS-PS3-4

Given the diagram representing a closed system at constant temperature:

• The mass of H₂O(l) equals the mass of H₂O(g).

• The volume of H₂O(l) equals the volume of H₂O(g).

• The number of moles of H₂O(l) equals the number of moles of H₂O(g).

• The rate of evaporation of H₂O(l) equals the rate of condensation of H₂O(g).