Inorganic Chemistry Answers

Two hydrogen atoms covalently bond to form a hydrogen molecule.

What is true about the hydrogen molecule?

• The hydrogen molecule has less energy than the two atoms.
• The hydrogen molecule has more energy than the two atoms.
• The hydrogen molecule has the same energy as the two atoms.
• The hydrogen molecule can have more or less energy than the hydrogen atoms.

it is NOT: The hydrogen molecule has more energy than the two atoms.

If a crystal lattice structure is so hard, what causes most ionic compounds to be brittle?

• Applying force, such as striking the crystal with a hammer, can shift one layer of ions, causing ions of different charges to align, repel each other, and fragment the crystal.
• Applying force, such as striking the crystal with a hammer, can release protons, causing ions of similar charges to align, repel each other, and dissolve the crystal.
• Applying force, such as striking the crystal with a hammer, can release electrons, causing ions to alter their charges, repel each other, and dissolve the crystal.
• Applying force, such as striking the crystal with a hammer, can shift ions, causing ions of similar charges to align, repel each other, and fragment the crystal.

(which of the answer is correct)

• it is not: Applying force, such as striking the crystal with a hammer, can release electrons, causing ions to alter their charges, repel each other, and dissolve the crystal.

What is true about ionic compounds?

Select all that apply.

• Electrons are not free to move.
• Properties of the compound are different than the properties of individual atoms that make the compound.
• Electrons are not involved in the formation of an ionic bond, since ions do not have valence electrons.
• They may have a positive or negative charge.

(more than one correct answer)

Which scenarios are definite signs that a chemical reaction has occurred?

Select all that apply.

• A piece of iron turns brown with rust.
• Water is heated and releases a water vapor.
• Two liquids are mixed together and release light.
• Blue and yellow paint mix to make green paint.

(more than one answer)

What are examples of a chemical reaction?

Select all that apply.

• 2AgI + Na₂S → Ag₂S + 2NaI
• H₂O → SiO₂
• SnO₂ → Sn + 2H₂O
• 4FeS + 7O₂ → 2Fe₂O₃ + 4SO₂

_{(select which of the options; more than one)}

What causes chemical reactions to occur?

• The products are more stable than the reactants.
• The products have more mass than the reactants.
• The products have less mass than the reactants.
• The products are less stable than the reactants.

(select which option)

The reaction of 1.00 mol of solid phosphorus with chlorine gas to form PCl3(g) releases 287.0 kJ of heat energy. The reaction of 1.00 mol of solid phosphorus with chlorine gas to form PCl5(g) releases 374.9 kJ of heat energy. Using Hess’s law, indirectly calculate the enthalpy change (in kJ.mol-1 ) for the following reaction.

What percentage of oxygen is present in the compound CaCO3.3Ca3(PO4)2? (A) 23.3% (B) 45.36% (C) 41.94% (D) 17.08%  

Calculate the total amount of energy (in kJ) necessary to raise the temperature of 2.00 L of ethanol (density = 0.7849 g/cm3) from 18 0C to its boiling point (78.3 0C) and then to fully vaporize the liquid. Assume that it is a closed system where no heat exchange with the surroundings take place.

(Given: Cethanol = 2.44 J/g·K; heat of vaporization of ethanol at 78.3 0C = 38.56 kJ/mol.)

Describe a reaction that can be used to distinguish between oxygen and ozone. Include an observation