What is meant by thermal equilibrium?
Two bodies have the same kinetic energy but their temperature is different.
Two bodies have different kinetic energy so their temperature is different.
Two bodies have the same kinetic energy so their temperature is the same.
Two bodies have different kinetic energy but their temperature is the same.
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Which of the following best explains why the reactions represented in the table are exothermic?
Balanced equation for the combustion of one mole of the compound | ΔHoc (kJ/mol ) |
|---|---|
C2H6 (g)+ 3.5 O2 (g) → 2CO2 (g) + 3H2O (l) | -1560 |
C3H8 (g)+ 4.5 O2 (g) → 3CO2 (g) + 4H2O (l) | -2020 |
The energy released in forming the bonds in the products is less than the energy required to break the bonds in the reactants.
The energy released in forming the bonds in the products is more than the energy required to break the bonds in the reactants.
The number of bonds in the product molecules is less than the number of bonds in the reactant molecules.
The number of bonds in the product molecules is more than the number of bonds in the reactant molecules.
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Which statement about energy diagrams is correct?
An energy diagram for an exothermic reaction has the reactants at higher energy than the products with a positive enthalpy change.
An energy diagram for an endothermic reaction has the reactants at lower energy than the products with a positive enthalpy change.
An energy diagram for an exothermic reaction has the reactants at lower energy than the products with a negative enthalpy change.
An energy diagram for an endothermic reaction has the reactants at lower energy than the products with a negative enthalpy change.
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A metal spoon is placed in a cup of hot coffee. Which statement best describes the heat transfer process?
Heat flows from the spoon to the coffee until they reach the same temperature.
Heat flows from the coffee to the spoon until they reach the same temperature.
The spoon heats up but does not affect the temperature of the coffee.
No heat transfer occurs because metals are good conductors.
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Which of the following statements are correct about the dissolution of an ionic compound?
I. The enthalpy of hydration is always an exothermic process
II. If the lattice energy is greater than the hydration energy, the dissolution process is endothermic
III. To calculate the enthalpy change of solution we use:
ΔHsolution = ΔHlattice - ΔHhydration
I only
I and II only
I and III only
I, II and III
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Ammonium chloride dissolves endothermically. What type of energy conversion takes place?
Chemical energy to kinetic energy
Kinetic energy to chemical energy
Kinetic energy to potential energy
Potential energy to chemical energy
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In the energy diagram shown above,
ΔH is exothermic and the forward activation energy is greater than the reverse activation energy
ΔH is endothermic and the reverse activation energy is greater than the forward activation energy
ΔH is exothermic and the reverse activation energy is greater than the forward activation energy
ΔH is endothermic and the forward activation energy is greater than the reverse activation energy
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The diagram above shows the heating curve for a substance.
Determine which of the following statements is true?
The specific heat capacities of the three states of matter are approximately the same.
The enthalpy of fusion is less than the enthalpy of vaporization.
The specific heat capacity of the gas is greater than the enthalpy of fusion.
The specific heat capacity of the gas is greater than that of the liquid.
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A student has two beakers containing water at two different temperatures. Beaker 1 contains 300 g of water at 40oC. Beaker 2 contains 100 g of water at 80oC.
Which of the following statements is true?
Beaker 2 contains water particles with higher average kinetic energy than beaker 1.
The water in beaker 1 has a higher specific heat capacity than beaker 2.
Beaker 2 has a higher thermal energy than beaker 1.
On mixing the two beakers, the final temperature of the water would be 60oC.
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The diagram above represents a heating curve for a typical substance.
Iodine is a solid that sublimes very easily.
Which statement would be true about the heating curve for iodine compared to the one above?
Line B would rise and become closer to the level of line D.
Line C would be shorter and steeper.
Line C would disappear and B and D would be at the same level.
Line D would become much shorter than line B.
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