chemistry help please much appreciated :)?

1. In the following equation, what represents the concentrations of the reactants?
K = [W][X] / [Y][Z]

In equilibrium expression, the concentrations of the products are put in the numerator ([W] and [X]), while that of the reactants are put in the denominator ([Y] and [Z]).

The answer: a. [Y] and [Z]


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2. For the reaction 2NO(g) + O₂(g) ⇌ 2NO₂(g) at a certain temperature, the equilibrium concentrations were found to be [NO₂] = 2.5 × 10⁻³ M, [O₂] = 4.0 × 10⁻² M, and [NO] = 1.5 × 10⁻³ M. Calculate the value of the equilibrium constant from this data.

Equilibrium constant, Keq = [NO₂] / {[NO]² [O₂]} = (2.5 × 10⁻³)² / {(1.5 × 10⁻³)² × (4.0 × 10⁻²)} = 6.9 × 10¹

The answer: 6.9 × 10¹


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3.
Consider the system 4NH₃(g) + 3O₂(g) ⇌ 2N₂(g) + 6H₂O(g) + heat. How will the amount of N2 be affected by an increase in the temperature?

The forward reaction is exothermic, while the backward reaction is endothermic.
Increase the temperature favors the endothermic reaction, such that the backward reaction.
Therefore, the equilibrium position shifts to the left, and thus the concentration of N₂ decreases. This leads to the decrease in the amount of N₂.

The answer: decrease