# Chemistry Problems for 9 – 28 – 16

Base your answers to questions 1 and 2 on the information below and on your knowledge of chemistry.

The equation below represents an equilibrium system of SO2(g), O2(g), and SO3(g).

The reaction can be catalyzed by vanadium or platinum.

2SO2(g) + O2(g) ↔ 2SO3(g) + energy

Base sus respuestas a las preguntas de la 1 y 2 en la siguiente información y su conocimiento de química.

La siguiente ecuación representa un sistema en equilibrio compuesto de SO2(g), O2(g), y SO3(g). La reacción puede ser catalizada por vanadio o platino.

2SO2(g) + O2(g) ↔ 2SO3(g) + energía

## Problem 1

Compare the rates of the forward and reverse reactions at equilibrium.

Compare las velocidades de las reacciones directa y reversa en equilibrio.

Discussion and Solution:

Since this is a reversible reaction, at equilibrium, the rates of the forward and reverse reactions are equal. The rates are the same.

## Problem 2

State how the equilibrium shifts when SO3(g) is removed from the system.

Exponga como el equilibrio cambia cuando el SO3(g) es removido del sistema.

Discussion and Solution:

When SO3(g) is removed from the system: The equilibrium will shift to favor the formation of SO3; The rate of the forward reaction is greater than the rate of the reverse reaction; The equilibrium will shift to favor the forward reaction; The equilibrium will shift to the right; and The concentrations of the reactants will decrease.

## Problem 3

Determine the volume of 2.00 M HCl(aq) solution required to completely neutralize 20.0 milliliters of 1.00 M NaOH(aq) solution.

Determine el volumen de una solución de 2.00 M HCl(aq) requerido para neutralizar completamente 20.0 mililitros de una solución de 1.00 M NaOH(aq).

Discussion and Solution:

We need to use the following equation, where Ma = molarity of the acid, Va = volume of the acid, Mb = molarity of the base, and Vb = volume of the base:

MaVa = MbVb

Since we are looking for Va, we divide both sides by Ma and substitute in what values we know and then simplify.

Va =  = 10.0 ml

## Problem 4

Given the balanced equation representing a reaction:

6Li + N2 → 2Li3N

Which type of chemical reaction is represented by this equation?
(1) synthesis
(2) decomposition
(3) single replacement
(4) double replacement

6Li + N2 → 2Li3N

¿Qué tipo de reacción química es representada por esta ecuación?
(1) síntesis
(2) decomposición
(3) desplazamiento simple
(4) doble desplazamiento

Discussion and Solution:

Since we are starting off with two elements (Li and N) and ending up with a compound (Li3N), this is an example of a synthesis reaction.

Choice (1)

In choice (2), we would have to start off with a compound and end up with two elements.

In choice (3), we would have to start off with an element and a compound. The element would then replace one of the elements found in the compound.

In choice (4), we would start off with two compounds, who would switch elements with each other.

## Problem 5

A rigid cylinder with a movable piston contains 50.0 liters of a gas at 30.0°C with a pressure of 1.00 atmosphere. What is the volume of the gas in the cylinder at STP?
(1) 5.49 L
(2) 45.0 L
(3) 55.5 L
(4) 455 L

Un cilindro rígido con un pistón movible contiene 50.0 litros de un gas a 30.0°C con una presión de un 1 atmósfera. ¿Cuál es el volumen del gas en el cilindro en STP?
(1) 5.49 L
(2) 45.0 L
(3) 55.5 L
(4) 455 L

Discussion and Solution:

For this we would use the combined gas law, where VI would be the initial volume of the gas, VF would be the final volume, PI would be the initial pressure, PF would be the final pressure, TI would be the initial temperature (in Kelvin), and TF would be the final temperature (in Kelvin).

VF =  = 45.0 L

Choice (2)

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