Topic 2 - Managing Chemical Processes Flashcards
What is a rate of reaction?
Rate of reactions refer to the rate at which chemical reactions occur over time. This can either be represented by the rate in which a product is formed or the rate in which a reactant is consumed.
How is rate of reaction measured?
The rate of reaction is measured using a concentration VS time graph. The gradient formula can be used to calculate average rate of reaction over an entire graph. Whereas, the gradient formula of a tangent at a specific point or differential calculus can be used to calculate the instantaneous rate of reaction at a specific point.
What does a steep slope mean in regards to rates of reaction?
A steep slope indicates a rapid rate of reaction.
What does a shallow slope mean in regards to rates of reaction?
A shallow slope indicates a slow rate of reaction.
What does zero slope mean in regards to rates of reaction?
Zero slope indicates no reaction occurring or the reaction has reached equilibria.
Does bond breaking require or release energy?
Bond breaking requires energy.
Does bond forming require or release energy?
Bond forming releases energy.
What occurs in relation to energy within all chemical reactions?
In all chemical reactions, there will be either a net release of energy into the surroundings or a net absorption of energy from the surroundings.
What happens to energy during an exothermic reaction?
Net release of heat energy to the surroundings, and the temperature of the surroundings increases.
What happens to energy during an endothermic reaction?
Net absorption of heat energy from the surroundings, and temperature of surroundings decreases.
Define enthalpy.
Enthalpy (H) is the total heat energy of the system at constant pressure and volume.
Define change in enthalpy.
The quantity of heat released when one mole of a substance reacts at a constant pressure.
Draw and explain an exothermic energy profile diagram.
Energy/heat is released. The energy of the reactants is greater than the energy of the products, as energy is emitted to surroundings. The change in enthalpy is negative.
Draw and explain an endothermic energy profile diagram.
Energy/heat is absorbed. The energy of the products is greater than the energy of the reactants, as energy is taken from the surroundings. The change in enthalpy is positive.
What does collision theory describe?
Collision theory is used to explain chemical reactions and the factors that affect the rate of the reaction. Reactants are particles that must collide with each other in order to react and form products.
What do successful collisions result in?
Product formation.
What do unsuccessful collisions result in?
No products formed and no chemical change.
What are the conditions for successful collisions?
- The reactant particles (molecules, atoms or ions) must collide.
- The colliding particles must have energy equal to or greater than the activation energy for the reaction.
- The reactant particles must collide in the correct orientation for a reaction to occur.
What is phrase used to describe the number of successful collisions per unit time?
The frequency of successful collisions.
What does the rate of reaction depend on?
The frequency of successful collisions.
What does a higher/lower frequency of successful collisions do to the reaction rate?
A higher frequency of successful collisions results in a quicker reaction rate. Whereas, a lower frequency of successful collisions results in a slower reaction rate.
What factors alter the rate of reaction?
Temperature, concentration, pressure, surface area, catalysis, and enzymes.
How does temperature impact rate of reaction?
The temperature of a substance is directly proportional to the average kinetic energy of the particles. This means that a higher temperature will result in faster particle movement due to a greater amount of kinetic energy. This increases the chances of molecules colliding with energy equal to or greater than the required activation energy. The frequency of successful collisions increases, thus increasing the rate of reaction.
How does concentration impact rate of reaction?
The higher the concentration, the more particles per unit volume. The closer particles are together, the more likely they are to collide. Thus, increasing the concentration of reactants, increases the frequency of successful collisions - causing a quicker rate of reaction.