Temperature is a measure of the amount of average kinetic energy of the atoms in a compound.
Concept: Understanding Temperature and Heat.3m
We're going to say that temperature is a measure of the thermal energy in a substance. We're going to say that temperature is independent on the amount of matter that we have. Basically, it doesn't matter how much we have a substance, the temperature is the temperature.
For example, if I have a cup of water versus a gallon of water, their masses are very different. One weighs more than the other. But if they're both at 100 degrees Celsius, they're both at 100 degrees Celsius. Basically, temperature doesn't depend on how much I have of the substance.
We're going to say that this is an example of an intensive property. An intensive property is a property that's not based on the mass or volume of an object. We're going to say besides temperature, we can say that boiling point, melting point, density, color, or hardness of metals are all considered intensive properties. None of them are based on the amount of mass or volume that I have of a particular substance.
Concepts like density, some of you may not know what that is, we'll get to that later on in the chapter and talk about it more in depth later on in the semester.
Now we're going to say heat is also a form of thermal energy, but unlike temperature, heat is very dependent on the amount of matter. Basically, we go back to that example of that cup of water versus that gallon of water. Now, they both might have the same temperature, but the amount of heat coming from them will be very different. The one gallon of water will have more heat coming from it because there's more of it. The cup of water will have much less heat emanating from its source because there's just less water to begin with.
We're going to say properties that are based on mass or volume are called extensive properties. If they're asking for the mass of an object, so mass is an extensive property, volume is, say moles, molar mass, anything dealing with weight or volume is an extensive property.
Temperature and heat are not as similar as you might think. Temperature is independent on the amount of matter, whereas heat is dependent on the amount of matter.
Example: Which of the following has the greatest amount of heat?2m
Remember that heat is based on the amount of matter and therefore represents an extensive property.
Concept: Kelvins, Celsius and Fahrenheit2m
Now that we've talked about temperature and heat, let's look at temperature conversions. In this course, we're going to have to know how to go from one set of temperatures to another. When it comes to temperatures, all you've got to really remember is we have three different units for temperature. We have Kelvins, which we say are large K. We have degrees Celsius. Then, we have degrees Fahrenheit.
All you have to do is remember these two simple equations and you'll be able to go through any one of these three. Remember, we're going to say that Kelvin equals 273.15 plus degrees Celsius. So if you know your degrees Celsius, just add 273.15 to it to get Kelvin. If you know your Kelvin, subtract 273.15 degrees to get degrees Celsius.
We're going to say the connection between Fahrenheit and Celsius is given by our second equation. We're going to say degrees Fahrenheit equals 1.8 times degrees Celsius plus 32. So if they give you Fahrenheit or Celsius, you can go between the two by just manipulating this equation. Just remember, temperature conversion can be really easy as long as you remember these two basic equations.
Although the SI unit for temperature is Kelvin you will required to know how to convert between Celsius and Fahrenheit as well.
Example: Convert the following units of temperature.
-115°C into Fahrenheit
73.23 K into Fahrenheit3m
Molecular bromine (Br2) has a boiling point of 58.8°C and a freezing point of 19°F.
a. Convert the boiling point to units of Fahrenheit (°F).
b. On a sunny 75°F day in Florida, would you expect bromine to exist as a solid, liquid or gas?
c. Are the freezing and boiling points of bromine considered physical or chemical properties?
If a solution has a temperature of 355 K, what is its temperature in degrees celsius?
What is the Kelvin temperature at 24°C?
A) 249 K
B) 11.4 K
C) -297 K
D) -249 K
E) 297 K
The average temperature on the summit of a mountain is 15°F. What is this temperature in Kelvin?
A) 242 K
B) 84 K
C) -282 K
D) 264 K
If the melting point of titanium metal is 1672°C, what is its melting point in Kelvin?
A) 1945 K
B) 3042 K
C) 1399 K
D) 897 K
The outside temperature is 250 K, what is the temperature in °F?
A. -9.67 °F
B. -23.15 °F
C. 973.67 °F
D. 909.67 °F
If the temperature is 178°F, what is the temperature in degrees celsius?
Gallium is a solid at room temperature, but has a melting point of 302.91 K. Compared to the temperature of the human body, 98.6°F, which is true?
A. Gallium melts at a lower temperature than body temperature, so it could melt in your hand if you hold it.
B. Gallium melts at a higher temperature than body temperature, so it will not melt in your hand if you hold it.
C. The melting point of gallium is less than the freezing point of water.
D. The melting point of gallium is greater than the boiling point of water.
Zirconium is a corrosion resistant metal that has a boiling point of 4682 K. What is the boiling point of this element in °F? Zirconium carbonate is used in lotions to treat poison ivy.