Chemical reactions occur when molecules or atoms collide, the bonds between atom
ID: 303701 • Letter: C
Question
Chemical reactions occur when molecules or atoms collide, the bonds between atoms are broken, and new bonds are formed. Breaking the bonds of the reactants requires energy; bond formation releases energy Which of the following statements regarding energy changes during a reaction are true? Decreasing the temperature decreases the kinetic energy of the reactants, and the reaction goes more slowly. If the energy of the products is higher than the energy of the reactants, the reaction is exothermic Increasing the amount of reactants increases the number of collisions, and the reaction goes faster The energy of a collision between atoms or molecules must be greater than or equal to the activation energy (Ea) for bonds to be broken. The activation energy (Ea) is the energy difference between the energy of the products and the energy of the reactants Reactants must collide, with proper orientation, with energy greater than or equal to the activation energy for a reaction to occur When the activation energy is high, the reaction rate is fast.Explanation / Answer
#CORRECT ANSWERS ARE 1, 3, 4 and 6
1- As the kinetic energy varies with temperature, decreasing temperature decreases k.e and hence reaction rate decreases as reaction needs energy.
3-As the number of reactants increases, they have more collisions and the rate of reactions increases.
4-The activation is the energy needed for molecules to collide. Hence this statement is also true.
6- some reactions need proper orientation and all reactions need energy greater than activation energy.
Now Why others are incorrect?
2-In exothermic rxn energy of reactants is higher than products . Hence incorrect.
5-Activation energy is difference between energy of reactants and the highest energy (energy of activated complex). So false.
7- activation energy needs to be low for a reaction to be fast.
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