WorksheetsEnergy changes and rate of reaction
Total questions: 15
Worksheet time: 8mins
What is an endothermic reaction
energy is absorbed
energy is released
energy is multiplied
energy is destroyed
Calculate ΔH for the following reaction:
CH4 (g) + O2 (g) ⇌ CO2 (g) + H2O (l)
Compound ΔH
CH4 (g) -74.8 kJ/mol
H2O (l) -285.8 kJ/mol
CO2 (g) -393.5 kJ/mol
-604.5 kJ/mol
-890.3 kJ/mol
890.3 kJ/mol
889.7 kJ/mol
Which of the following correctly describes processes that happen during reactions?
Bonds are broken in reactants, which is an exothermic process that takes in energy
Bonds are broken in reactants, which is an endothermic process that gives out energy
Bonds are made in products, which is an endothermic process that takes in energy
Bonds are made in products, which is an exothermic process that gives out energy
The combustion of ethane (C2H6) is represented by the equation:
2C2H6(g) + 7O2(g) 4CO2(g) + 6H2O(l)
the rate of consumption of ethane is seven times faster than the rate of consumption of oxygen.
the rate of formation of CO2 equals the rate of formation of water.
CO2 is formed twice as fast as ethane is consumed.
he rate of consumption of oxygen equals the rate of consumption of water.
The speed of a chemical reaction
between ions in aqueous solution is extremely rapid because there are no bonds that need to be broken.
is independent of the amount of contact surface of a solid involved.
is constant no matter what the temperature is.
varies inversely with the absolute temperature.
When the concentration of reactant molecules is increased, the rate of reaction increases. The best explanation is: As the reactant concentration increases,
the activation energy increases.
the rate constant increases.
the average kinetic energy of molecules increases.
the frequency of molecular collisions increases.
Magnesium needs to be heated before it reacts with oxygen in the air. What conclusion can you draw from this?
The reaction is reversible
The reaction has a high activation energy
The reaction is exothermic
Magnesium has a high melting point
Which of the following reactions releases most energy to the surroundings?
Reaction energy change = -456 kJ/mol
Reaction energy change = +547 kJ/mol
Reaction energy change = +1456 kJ/mol
Reaction energy change = -38 kJ/mol
The equations for three reactions are given below.
Reaction 1 H2 –> 2H
Reaction 2 HCl –> H + Cl
Reaction 3 2H + O –> H2O
Which reaction/s is/are exothermic?
Reaction 3 only.
Reaction 1 and 2 only.
Reaction 1 and 3 only.
Reaction 2 and 3 only.
The H-H bond energy is 436 kJ/mol and the Cl-Cl bond energy is 242 kJ/mol.
What is the H-Cl bond energy?
247 kJ
431 kJ
494 kJ
862 kJ
Energy is a
point function
extensive property
property of the system
all of the mentioned
The formation of a chemical bond releases energy. True or false?
true
false
The enthalpy of combustion of glucose is -2808 kJ mol-1. Which one of the following statements regarding this process is false?
the precess is exothermic
The products of the combustion of glucose are less stable than glucose itself
energy is liberated
Which are ways to increase the rate of a reaction?
increase the surface area of the reactants
use a catalyst
heat the reactants
decrease the concentration of the reactants
The reaction between hydrogen and bromine to form hydrogen bromide can be written as
H2(g) + Br2(g) ===> 2HBr(g)
Use the bond energies shown to calculate the energy change that takes place when hydrogen bromide is formed according to the above equation.
Bond energies in kJ/mol:
H-H = 435
Br-Br = 200
H-Br = 370
270 kJ taken in
270 kJ given out
105 kJ taken in
105 kJ given out
