under rate of reactions
Fe^2+ + Cr2o7^2- » Cr^3+ +Fe^3+
The equation you provided represents a redox reaction between iron ions (Fe^2+) and dichromate ions (Cr2O7^2-). This reaction can be written as:
6 Fe^2+ (aq) + Cr2O7^2- (aq) → 6 Fe^3+ (aq) + 2 Cr^3+ (aq)
To understand the rate of this reaction, we need to consider the factors that affect reaction rates. The rate of a chemical reaction is defined as the change in concentration of a reactant or product per unit of time.
Factors that affect the rate of a reaction include:
1. Concentration of reactants: Increasing the concentration of the reactants generally leads to an increase in reaction rate. By adding more Fe^2+ or Cr2O7^2-, the chances of successful collisions between the reactant molecules increase, leading to a faster reaction.
2. Temperature: Raising the temperature generally increases the rate of a reaction. This is because higher temperature provides more kinetic energy to the reactant molecules, causing them to move faster and collide with more energy, leading to more successful collisions and a faster reaction.
3. Catalysts: Catalysts are substances that can speed up a reaction without being consumed in the process. In this reaction, there are no catalysts mentioned, but catalysts are commonly used in many redox reactions to increase the reaction rate.
4. Surface area: For reactions involving solid reactants, increasing the surface area of the solid (e.g., by grinding it into smaller particles) can increase the reaction rate. This is because more surface area allows for more contact between reactant particles and a higher likelihood of successful collisions.
To specifically calculate the rate of the reaction, you would need additional information, such as the initial concentrations of Fe^2+ and Cr2O7^2-. These concentrations would be needed to determine the rate of change in concentration over time.
It is also worth noting that the overall rate expression for a reaction is determined experimentally and depends on the individual reaction mechanism. The rate expression can involve powers of the concentrations of the reactants, as well as temperature, pressure, and other factors.