Chapter 8 SABIS Grade 10 Part 3

Chapter 8 Third Lesson :

🔗 Chemical Bond Energy and Energy Changes in Substances

Part 1: 🔍 Chemical Bond Energy

8.2.3 Variation of Potential Energy as Two H Atoms Approach

💫 Approaching Hydrogen Atoms Let's observe the dance of potential energy as two hydrogen atoms get closer and form a bond! 🕺💃

Sample Question 16

🧠 Understanding the Potential Energy Changes When two hydrogen atoms approach each other from an infinite distance:

a) Initially, their total potential energy decreases because the attractive forces are initially stronger.

b) Initially, their total potential energy increases because the attractive forces are initially stronger.

c) At a certain distance, the potential energy of the atoms reaches a minimum value, and this distance is called the bond length.

d) At a certain distance, the potential energy of the atoms reaches a maximum value, and this distance is called the bond length.

e) If the two atoms approach closer than the bond length, the potential energy of the system increases rapidly.

Sample Question 17

🧠 Bond Energy of the Hydrogen Molecule When two hydrogen atoms form a bond, bond energy is the energy needed to:

a) Bring the two nuclei to touch each other.

b) Make the distance between the two nuclei infinite.

c) Burn the hydrogen to water.

d) Change them to H2 gas.

e) Tie the two hydrogen atoms together.

Part 2: 🔍 Bond Energy and Energy Changes in Molecules

8.2.4 Vibrational Energy of Molecules

🎯 Vibrational Energy Let's explore how molecules vibrate with energy! It's like witnessing a molecular dance party in motion! 🎉

8.2.5 Rotational Energy of Molecules

🌀 Rotational Energy Molecules not only vibrate but also spin around! It's like watching tiny molecular acrobats perform graceful spins! 🤸

8.2.6 Heat Content

🌡️ Measuring Heat Content The heat content of a substance is like its inner energy bank, storing energy from various sources! 💰

8.2.7 Motion of Particles of an Ideal Gas

🚀 Motion of Gas Particles In the world of gases, particles zoom around at incredible speeds, like energetic little rockets in motion! 🚀

8.2.8 Energy Changes on Warming

🔥 Energy Changes During Warming As we warm up substances, energy swirls and transforms, like awakening the hidden potential within! 🌪️

Sample Question 18

🧠 Microscopic Changes When a Solid is Warmed Which of the following changes take place when a solid is warmed?

a) Warming the solid increases the kinetic energy of the back-and-forth motions of the molecules about their regular crystal positions.

b) If the solid is heated a little more, this random movement can destroy some of the nuclei of the atoms.

c) At the temperature above which the kinetic energy of the particles causes so much random movement that the lattice is no longer stable, a phase change occurs: the solid melts.

Sample Question 19

🧠 Microscopic Changes When a Liquid is Warmed Which of the following changes take place when a liquid is warmed?

a) Warming the liquid increases the kinetic energy of the back-and-forth motions of the molecules to the extent where a molecule can move within the liquid from place to place.

b) If the liquid is heated a little more, this random movement can destroy some of the nuclei of the atoms.

c) At the temperature above which the kinetic energy of the particles causes so much random movement that the molecules of the liquid can move far from each other, a phase change occurs: the liquid evaporates.

Sample Question 20

🧠 Microscopic Changes When Gases are Heated Strongly Which of the following changes take place when a gas is heated strongly?

a) Warming the gas to the extent where the vibrational energy becomes equal to or more than the bond energy between atoms, the atoms move far apart.

b) At temperatures higher than 6000K, the only molecules that can exist are those that have between 2 and 10 atoms.

c) At temperatures that reach millions of degrees, nuclear reactions can take place.

Sample Question 21

🧠 Relative Magnitude of Heat Involved in Physical & Chemical Changes Which of the following is correct about the relative magnitude of the heat involved in physical and chemical changes?

a) Phase changes usually involve energies of tens of kilojoules per mole.

b) Chemical reactions usually involve energies of tens of kilojoules per mole.

c) Chemical reactions usually involve energies of about a thousand kilojoules per mole.

d) Chemical reactions usually involve energies of several million kilojoules per mole.

e) Chemical reactions usually involve energies of several hundred to several thousand kilojoules per mole. Thus, we see that the energies involved in chemical reactions are usually 10 to 100 times larger than those involved in phase changes.

Congratulations! 🎉 You've completed Lesson 3 and explored the fascinating world of chemical bond energy, energy changes in substances, and the dance of molecules. Keep up the excellent work, and get ready to dive deeper into the captivating realm of chemistry! 🧪🚀