IB Chemsl Intro To Energetics

When solid potassium chloride is added to water, the temperature of the liquid goes down. Which conclusion can be made from this observation?

• The process is exothermic.

• The process is endothermic.

• Very little potassium chloride dissolves in water.

• All solids dissolve with a temperature decrease.

When steam is passed through white-hot coke, a reaction occurs and the temperature of the coke falls.What does this indicate?

• Coke contains impurities

• The reaction is exothermic

• Coke is an oxidising agent

• The reaction is endothermic

The equations for three changes are given below: Which of the following changes are endothermic?              

• Reaction 1 only

• Reactions 1 and 3 only

• Reactions 1 and 2 only

• Reactions 2 and 3 only

Which of the following statements DOES NOT describe the enthalpy level diagram found below:   

• The reaction is endothermic.

• Energy is absorbed by the system.

• The total energy change for bond formation is greater than that for bond breaking.

• The product possesses more energy than the reactants.

Which process is BEST represented by the energy level diagram found below:  

• Adding ammonium thiocyanate to barium hydroxide

• Melting of mercury metal

• Sublimation of dry ice

• Neutralization of acid and base

A student was asked to write down five pieces of information that could be obtained from the equation below: Which one of the following pieces of information is INCORRECT?    

• Magnesium chloride is soluble in water

• Total energy of the products is greater than that of the reactants

• One mole of magnesium produces one mole of hydrogen molecules

• Total energy of the products is less than that of the reactants

Which of the following statements regarding the reaction below is NOT correct? Heat of reaction is also given.    

• The energy of the reactants is less than that of the product.

• For each mole of the solid product formed in the reaction, 10.2 kJ of heat is released.

• The energy involved in bond forming is greater than that of bond breaking.

• If the reaction is carried out in an insulated container, the temperature in the container would increase.

The dissolving of potassium iodide in water is an endothermic process. Which graph shows the temperature changes that occur when potassium iodide is stirred with water until no further change in temperature is observed?

• A

• B

• C

• D

The formation of hydrogen iodide from hydrogen and iodine is an endothermic reaction.      H-H + I-I→ H-I + H-I         What may be deduced from this information?

• The total energy change in bond formation is less than that of bond breaking.

• The products possess less energy than the reactants.

• The formation of H-I bonds absorbs energy.

• The number of bonds broken is greater than the number of bonds formed.

  When 1 mole of chlorine gas reacts to form hydrogen chloride, the enthalpy change is -184 kJ/mol. Calculate the energy change when 14.2 grams of chlorine reacts completely with hydrogen.