1. In chemistry, enthalpy changes are defined as_____. Select one: a. being posi

Question

1. In chemistry, enthalpy changes are defined as_____.

Select one:

a. being positive for endothermic (heat-absorbing) processes;

b. all options are correct;

c. being negative for exothermic (heat-generating) processes;

2.The enthalpy change associated with the hydration process is called the heat of hydration, true or false?

Select one:

True

False

3.What are open systems, closed systems and isolated systems?

Select one:

a. an isolated system cannot exchange mass and energy with its surroundings; an open system allows the transfer of energy but not mass; a closed system does not allow the transfer of either mass or energy; (d) all options are incorrect;

b. an open system can exchange mass and energy with its surroundings; an isolated system allows the transfer of energy but not mass; a closed system does not allow the transfer of either mass or energy;

c. an open system can exchange mass and energy with its surroundings; a closed system allows the transfer of energy but not mass; an isolated system does not allow the transfer of either mass or energy;

4.Lattice energy (U) is defined as: the energy required to completely separate one mole of a solid ionic compound into gaseous ions, true or false?

Select one:

True

False

Explanation / Answer

1. For an Exothermic reaction, Enthalpy change is negative (Heat released )

For an Endothermic reaction, Enthalpy change is postive (Heat absorbs)

Answer: Both Options are Correct. Option b is the corect answer.

2. .The enthalpy change associated with the hydration process is called the heat of hydration TRUE

Heat of Hydration is also called Enthalpy of Hydration.

3.

Open System: Exchanges both Energy and Matter with the Surroundings.

Closed System: Exchanges only Energy with the Surroundings. No Matter exchanges

Isolated System: Exchanges neither Energy nor Matter with the Surrroundings.

Option c is the right answer

4. Lattice energy (U) is defined as: the energy required to completely separate one mole of a solid ionic compound into gaseous ions. Its TRUE

lLattice Energy can be defined in two ways:

1.  the lattice energy is the energy required to break an ionic solid and convert its component atoms into gaseous ions. In this case, the Lattice energy is Positive (Endothermic reaction)

2.  It is the energy released when gaseous ions bind to form an ionic solid.

In this case, the Lattice energy is Negative (Exothermic reaction)

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