# Short-Questions

Fast solutions for complex problems

37

## What changes the rate constant of a reaction?

The rate equation shows the effect of changing the concentrations of the reactants on the rate of the reaction. If you change the temperature or the catalyst, for example, the rate constant changes.

Is rate constant same for a reaction?

D. The rate constant is a proportionality factor in the rate law of chemical kinetics that relates the molar concentration of reactants to reaction rate. It is also known as the reaction rate constant or reaction rate coefficient and is indicated in an equation by the letter k.

### Does the rate constant k vary over time?

The value of this coefficient k will vary with conditions that affect reaction rate, such as temperature, pressure, surface area, etc. A smaller rate constant indicates a slower reaction, while a larger rate constant indicates a faster reaction.

How does the value of rate constant vary with reaction?

The rate of a reaction depends on the temperature, and concentration of the reactants, but the value of k, the rate constant does not. If this ratio is constant, then the value of k will be constant, and will thus not be dependent upon the concentration of the reactants.

#### What are the 5 factors that affect the rate of reaction?

We can identify five factors that affect the rates of chemical reactions: the chemical nature of the reacting substances, the state of subdivision (one large lump versus many small particles) of the reactants, the temperature of the reactants, the concentration of the reactants, and the presence of a catalyst.

What are the 4 factors that affect the rate of reaction?

The factors that affect reaction rates are:

• surface area of a solid reactant.
• concentration or pressure of a reactant.
• temperature.
• nature of the reactants.
• presence/absence of a catalyst.

## Which would speed up a reaction?

Catalysts speed up chemical reactions. How does concentration affect the rate of a reaction? Increasing the concentration of the reactants will increase the frequency of collisions between the two reactants.

What is half life period of a reaction?

The half-life of a reaction is the time required for a reactant to reach one-half its initial concentration or pressure. For a first-order reaction, the half-life is independent of concentration and constant over time.

### What is rate constant k?

The specific rate constant (k) is the proportionality constant relating the rate of the reaction to the concentrations of reactants. A large value of the rate constant means that the reaction is relatively fast, while a small value of the rate constant means that the reaction is relatively slow.

What happens to K when you reverse the reaction?

The equilibrium expression written for a reaction written in the reverse direction is the reciprocal of the one for the forward reaction. K’ is the constant for the reverse reaction and K is that of the forward reaction….

Equation Equilibrium Constant
N2(g) + O2(g) NO2(g) Kc = 4.1 x 10-9

#### What are three requirements for a reaction to proceed?

Three things must happen for a reaction to occur.

• Molecules must collide.
• Molecules must collide with enough energy to begin to break the old bonds so new bonds can form. ( Remember activation energy)
• Molecules must collide with the correct orientation.

Does rate constant depends on reactant concentration?

The rate constant (k) of a rate law is a constant of proportionality between the reaction rate and the reactant concentration. The exponent to which a concentration is raised in a rate law indicates the reaction order, the degree to which the reaction rate depends on the concentration of a particular reactant.