Thermal Energy and Phase Changes

The video tutorial explains the concept of heating curves, which typically start with a solid below its melting point and progress through various phase changes until reaching a gas. Using water as an example, the tutorial calculates the energy required to change 15 grams of ice at -40°C to steam at 130°C. The process is broken down into five steps, each requiring specific formulas and constants. The tutorial covers the use of specific heat, heat of fusion, and heat of vaporization in these calculations, ultimately determining the total energy needed for the transformation.

What is the initial phase of a substance in a typical heating curve?

• Plasma

• Solid

• Liquid

• Gas

How many steps are involved in calculating the energy needed to change water from ice to steam?

• Three

• Seven

• Five

• Nine

Which formula is used when there is a change in temperature?

• Delta H = m * CP * delta T

• Delta H = m * CP

• Mass times heat of vaporization

• Mass times heat of fusion

What is the specific heat of liquid water in joules per gram degree Celsius?

• 3.5

• 4.184

• 5.2

• 2

What is the heat of fusion of water in joules per gram?

• 100

• 4184

• 2260

• 334

During which interval is the formula mass times heat of vaporization used?

• When melting ice

• When boiling water

• When heating ice

• When cooling steam

What is the total energy required to convert 15 grams of ice at -40°C to steam at 130°C?

• 600000 Joules

• 40731 Joules

• 407310 Joules

• 500000 Joules

What is the final temperature of steam in the last interval?

• 200°C

• 150°C

• 130°C

• 100°C

Which phase change occurs at constant temperature?

• Melting

• Freezing

• Heating

• Cooling

What is the specific heat of steam in joules per gram degree Celsius?

• 2

• 4.184

• 3.5

• 5.2