Intermolecular Forces and Phase Changes

Which of the following is an example of a dipole-dipole interaction?

• The attraction between two nonpolar molecules

• The attraction between a hydrogen atom and a highly electronegative atom

• The attraction between two polar molecules

• The attraction between ions in an ionic compound

Answer explanation

Dipole-dipole interactions occur between polar molecules due to their permanent dipoles. The attraction between two polar molecules is a classic example, as their positive and negative ends attract each other.

How does increasing temperature generally affect the kinetic energy of particles in a substance?

• It decreases the kinetic energy

• It has no effect on the kinetic energy

• It increases the kinetic energy

• It causes the particles to stop moving

Answer explanation

Increasing temperature provides more energy to the particles, causing them to move faster. This increase in motion results in higher kinetic energy, making 'It increases the kinetic energy' the correct choice.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

During the phase transition from liquid to gas, what happens to the energy of the system?

• Energy is absorbed

• Energy is released

• Energy remains constant

• Energy is destroyed

Answer explanation

During the phase transition from liquid to gas, energy is absorbed to overcome intermolecular forces. This energy input is necessary for molecules to escape into the gas phase, making 'Energy is absorbed' the correct choice.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Compare the arrangement of particles in solids, liquids, and gases.

• Particles in solids are more spread out than in gases

• Particles in liquids are more tightly packed than in solids

• Particles in gases are more spread out than in liquids

• Particles in solids are more spread out than in liquids

Answer explanation

In gases, particles are far apart and move freely, while in liquids, they are closer but still able to flow. Solids have tightly packed particles that vibrate in place. Thus, gases are more spread out than liquids.

Explain why hydrogen bonding is stronger than London dispersion forces.

• Hydrogen bonds involve the sharing of electrons

• Hydrogen bonds occur between nonpolar molecules

• Hydrogen bonds involve a permanent dipole and are stronger due to the high electronegativity of atoms like oxygen and nitrogen

• Hydrogen bonds are weaker because they only occur in water

Answer explanation

Hydrogen bonds are stronger than London dispersion forces because they involve a permanent dipole due to the high electronegativity of atoms like oxygen and nitrogen, leading to stronger interactions compared to temporary dipoles in dispersion forces.

Predict the effect of decreasing temperature on the state of matter of a gas.

• The gas will become a liquid

• The gas will become a solid

• The gas will remain a gas

• The gas will become plasma

Answer explanation

Decreasing temperature reduces the kinetic energy of gas molecules, leading them to come closer together. Eventually, this causes the gas to condense into a liquid, making 'The gas will become a liquid' the correct choice.

Tags

NGSS.MS-PS1-4

Analyze the energy changes when ice melts into water.

• Energy is released as heat

• Energy is absorbed as heat

• Energy remains constant

• Energy is converted into mass

Answer explanation

When ice melts into water, energy is absorbed as heat to break the bonds between ice molecules. This process requires energy input, making 'Energy is absorbed as heat' the correct choice.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Which state of matter has a definite volume but no definite shape?

• Solid

• Liquid

• Gas

• Plasma

Answer explanation

The state of matter that has a definite volume but no definite shape is a liquid. Liquids take the shape of their container while maintaining a constant volume, unlike solids (definite shape and volume) and gases (no definite shape or volume).

Identify the type of intermolecular force present in a sample of water.

• London dispersion forces

• Dipole-dipole interactions

• Hydrogen bonding

• Ionic bonding

Answer explanation

Water exhibits hydrogen bonding due to the presence of highly polar O-H bonds. This strong intermolecular force arises from the attraction between the hydrogen atom of one water molecule and the oxygen atom of another.

What is the primary reason gases are compressible while solids are not?

• Gases have stronger intermolecular forces

• Gases have more space between particles

• Solids have more space between particles

• Solids have weaker intermolecular forces

Answer explanation

Gases are compressible because their particles are far apart, allowing them to be pushed closer together. In contrast, solids have tightly packed particles, leaving little space for compression.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS2-5