- Write the balanced equation for the decomposition of hydrogen peroxide.
- According to Charles’s law, what is the relationship between temperature and pressure?
- Atmospheric pressure depends on the altitude (or height) of your location. How should the air pressure change if you were in Denver, Colorado, which is 1.5 kilometers (1 mile) above sea level?
- Considering that catalysts are not consumed in a reaction, how do you think increasing the amount of catalyst would affect the reaction rate for the decomposition of hydrogen peroxide?
The Correct Answer and Explanation is :
The decomposition of hydrogen peroxide (( H_2O_2 )) into water (( H_2O )) and oxygen (( O_2 )) gas is represented by the balanced chemical equation:
[ 2 H_2O_2 (l) \rightarrow 2 H_2O (l) + O_2 (g) ]
Charles’s Law and the Relationship Between Temperature and Pressure
Charles’s Law states that, for a given quantity of gas at constant pressure, the volume of the gas is directly proportional to its absolute temperature. This implies that if the temperature of the gas increases, the volume of the gas also increases proportionally, and vice versa, assuming the pressure remains constant. While Charles’s law directly relates temperature and volume, it implies that if volume cannot change (e.g., in a rigid container), an increase in temperature will result in an increase in pressure and vice versa.
Atmospheric Pressure and Altitude
Atmospheric pressure decreases as altitude increases. This is because the higher the altitude, the less air there is above the area pressing down. Denver, Colorado, situated about 1.5 kilometers (approximately 1 mile) above sea level, would have a lower atmospheric pressure compared to locations at sea level. This is due to the thinner layer of air above it exerting less pressure. As a result, the atmospheric pressure in Denver would be significantly lower than that of a coastal city.
Effect of Increasing the Amount of Catalyst on the Reaction Rate
Catalysts work by providing an alternative pathway for a chemical reaction that has a lower activation energy. This makes the reaction occur more rapidly. In the decomposition of hydrogen peroxide, common catalysts include manganese dioxide (( MnO_2 )) or potassium iodide (( KI )).
Increasing the amount of catalyst in a reaction generally increases the reaction rate up to a certain point. This is because more catalyst means more surface area for the reaction to occur, which can facilitate the conversion of more reactant molecules into products per unit of time. However, after a certain point, adding more catalyst will not continue to increase the rate, as all the reactant molecules may already be engaged in the reaction as quickly as they can be supplied. At this saturation point, the reaction is occurring as fast as possible, limited by factors other than the amount of catalyst, such as the concentration of the reactants or the temperature of the system.
Thus, while initially increasing the catalyst amount can lead to faster reactions, this effect diminishes once the reaction rate reaches its maximum feasible speed under given conditions.