(a) What are the units usually used to express the rates of reactions occurring in solution? (b) From your everyday experience, give two examples of the effects of temperature on the rates of reactions. (c) What is the difference between average rate and instantaneous rate?

The units typically used to express the rates of reactions in solutions are moles per liter per unit time (Molarity/time). Usually, it is expressed as moles per liter per second (M/s) or moles per liter per minute (M/min). To better understand reaction rates, we measure the change in the concentration of reaction participants over time.

1. Food Spoilage: At higher temperatures, microorganisms and enzymes in food react faster, causing food to spoil more quickly. On the other hand, when food is kept in the fridge, the low temperature slows down the reaction rate, preserving the food for a longer period. 2. Cold Packs and Hot Packs: Chemical reactions within cold packs and hot packs are activated by changing temperatures. When a cold pack is activated, an endothermic reaction takes place, which means that energy (in the form of heat) is absorbed from the surroundings, making the pack feel cold. On the other hand, when a hot pack is activated, an exothermic reaction takes place, releasing energy in the form of heat and making the pack feel hot.

The average rate is the change in concentration of reactants or products over a specified period. It is calculated by taking the difference in concentrations at two different time points and dividing by the change in time. The average rate gives an indication of the overall reaction rate over a time interval. Instantaneous rate, on the other hand, refers to the rate of a reaction at a specific point in time. It is calculated by taking the derivative of concentration with respect to time or by using the tangent of the concentration-time graph at that particular instant. The instantaneous rate gives us information about how the reaction is proceeding at that specific moment. In summary, while the average rate provides a general idea of the reaction rate over a specific time interval, the instantaneous rate offers more detailed information on the rate of the reaction at a specific point in time.