Factors Affecting Reaction Rates

Flashcards about factors affecting reaction rates.

How does increasing the concentration of a solution affect the rate of a chemical reaction?

Increasing the concentration increases the frequency of collisions between reacting particles, generally leading to an increased reaction rate.

Why is a reaction in pure oxygen faster than the same reaction in air?

Oxygen has a higher concentration in pure oxygen than in air (20%), resulting in more frequent collisions between reacting particles.

What happens to the rate of reaction when there is a low concentration of reactant particles per unit volume?

The frequency of collision is low, the number of successful/effective collisions will be low, and the rate of reaction will be slow.

What happens to the rate of reaction when there is a high concentration of reactant particles per unit volume?

The frequency of collision is high, the number of successful/effective collisions will be high, and the rate of reaction will be fast.

How does increasing the surface area of a solid affect the rate of reaction?

Increasing the surface area exposes more particles for collision, increasing the frequency of collisions and leading to a faster rate of reaction.

Why does powdered marble react faster than marble chips?

Powdered marble has a much greater surface area than marble chips, exposing more particles for collision.

How does stirring a solid in a liquid affect the rate of dissolving?

Stirring increases the surface area of contact, which increases the rate of reaction.

What is the effect of higher kinetic energy on reaction rates?

When temperature is increased the particles gain kinetic energy and this has two effects. Firstly they move faster and therefore collide with other particles more often. Secondly, and more importantly, since the particles have more energy, it is more likely that the collisions will have enough energy to result in a reaction.

How does an increase in temperature affect the frequency and effectiveness of collisions?

An increase in temperature increases both the frequency of collisions and the effectiveness of collisions, as particles have more energy to overcome the activation energy barrier.

How does lowering the temperature affect a reaction's rate?

The particles have a lower kinetic energy, lowering the frequency of collisions. The number of collisions reaching activation energy is lessened, therefore resulting in less successful collisions and a lower rate of reaction.

How do catalysts increase rate of reaction?

The catalyst achieves this by providing an alternative pathway that has a lower activation energy requirement than normal.

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

A catalyst increases the rate of reaction by providing an alternative pathway with a lower activation energy requirement, and the catalyst is not consumed in the reaction.

According to the collision theory, what three criteria must be met for a reaction to occur?

The particles of the reactants must collide, the particles of the reactants must have sufficient energy (more than the activation energy), and the particles must collide with correct orientation.

How does increasing the concentration of sulfuric acid affect the reaction rate with magnesium ribbon?

Increasing the concentration of acid increases the frequency of collisions between H3O+ ions and magnesium atoms, causing the reaction to speed up.

How does using powdered magnesium instead of magnesium ribbon affect the reaction rate with sulfuric acid?

Using powdered magnesium increases the surface area, leading to a higher frequency of collisions between H3O+ ions and magnesium atoms, increasing the reaction rate.

How does increasing the temperature affect the reaction rate between magnesium ribbon and sulfuric acid?

Increasing the temperature increases the kinetic energy of the particles, resulting in more frequent and forceful collisions, and a higher proportion of successful collisions, thus speeding up the reaction.

What is the effect of adding copper granules to the reaction between zinc and sulfuric acid?

Copper acts as a catalyst, providing an alternative pathway with a lower activation energy, increasing the frequency of successful collisions and the rate of reaction.