Which one of the following factors would not speed up a chemical reaction
None
most important factor:
do not watch the clock!
To determine which factor would not speed up a chemical reaction, we need to understand the factors that can affect the rate of a chemical reaction. The factors that can influence the rate of a reaction are temperature, concentration of reactants, surface area, pressure (for gases), and the presence of catalysts.
Temperature: Increasing the temperature generally increases the kinetic energy of molecules, causing them to move faster and collide more frequently, thus speeding up the reaction.
Concentration: When the concentration of reactants is increased, there are more particles available to collide with each other, leading to more frequent collisions and increased reaction rate.
Surface area: Breaking a solid reactant into smaller particles with a larger surface area increases the exposed surface available for reaction, allowing for more collisions and faster reaction rates.
Pressure: Increasing the pressure (for gas-phase reactions) leads to a higher concentration of gas molecules in a given volume, increasing the frequency of collisions and enhancing the reaction rate.
Catalysts: Catalysts are substances that can speed up a reaction without being consumed themselves. They work by providing an alternative reaction pathway with lower energy barriers, enabling the reactants to undergo the reaction more readily.
Now, considering these factors, the one that would not speed up a chemical reaction is concentration. Decreasing the concentration of reactants reduces the number of reactant particles available for collisions, which decreases the reaction rate. However, increasing the concentration would speed up the reaction, as explained earlier.
In summary, the factor that would not speed up a chemical reaction is decreasing the concentration of reactants. Increasing temperature, surface area, pressure (for gases), and using catalysts all have the potential to speed up a chemical reaction.