INTRODUCTION TO THERMOCHEMISTRY

The change in enthalpy of an exothermic reaction is

• Always positive

• Always negative

• Can either be positive or negative

• None of the above

If a reaction is ENDOTHERMIC, temperature of the surroundings would ...........................

• increase

• decrease

• remain constant

• fluctuate

Do reactants in an endothermic reaction have a higher or lower energy than the products?

• Lower

• Higher

What is the chemical structure identified at the top of the curve?

• Reactants

• Products

• Catalyst

• Activated complex

In an endothermic reaction, the reactants are ...................... stable than the products.

• more

• less

Which arrows indicates enthalpy change?

• Arrow A

• Arrow B

• Arrow C

• Arrow D

The quantity of heat needed to raise the temperature of 1.0g sample of a substance 1.0 degree is called its .......................................

• heat capacity

• enthalpy

• specific heat

• kinetic energy

If 25 J are required to change the temperature of 5.0 g of substance Y by 2.0 ^oC, what is the specific heat of substance Y?

• 250 J/g^oC

• 10 J/g^oC

• 63 J/g^oC

• 2.5 J/g^oC

How much energy is required to change the temperature of 2.00 g aluminium from 20.0 ^oC to 25.0 ^oC? The specific heat of aluminium is 0.902 J/g^oC.

• 2.3 J/g^oC

• 9.0 J/g^oC

• 0.36 J/g^oC

• 0.090 J/g^oC

The reaction is .........................., and therefore heat is .......................... by the reaction.

• exothermic, released

• exothermic, absorbed

• endothermic, released

• endothermic, absorbed