Unit 2 Flashcards
What are the 5 properties of gas?
- Gases are compressible
- Gases expand as the temperature is increased
- Gases have very low viscosity (ability to float)
- Gases have much lower densities than solids or liquids
- Gases are miscible
Explain why gases are compressible
The volume of a gas decreases dramatically when pressure is exerted on the gas because molecules are spaced further apart in gases than in liquids.
Why do gases expand as temperature is increased?
If pressure remains constant, molecules are moving faster\have more kinetic energy.
Why do gases have low viscosity?
Because they have low resistance to float. Gases flow through pipes more freely than liquids such as water. Gases will escape quickly through small openings in their containers.
Why do gases have lower densities than solids or liquids?
Because there is more space between molecules
Why are gases miscible?
Because they mix completely and evenly with each other when put in the same container
What is KMT
KMT stands for kinetic molecular theory and provides a scientific model for explaining the behaviour of gases.
What is an ideal gas?
A hypothetical gas that obeys all gas laws perfectly under all conditions
What is a real gas
A real gas deviates from and ideal gas under certain conditions
>real gases behave nearly like ideal gases at relatively low pressure and high temperatures such as STP and SATP conditions
KMT assumptions for ideal gases?
-Gas molecules are very far apart compared to their size. In other words, the molecules’ size is negligible.
-Gas molecules are in constant, random, straight-line motion because no forces exist between them.
-Gas molecules undergo perfectly elastic collisions in which no energy is lost and collisions (and rebounds) occur very quickly
Interpretation for real gases
-For high pressures, the molecules are forced much closer together and their size becomes significant. In other words, the empty space available is less than the size of the container.
-As the temperature decreases, the molecules slow down. At some point, the intermolecular attractions may cause the molecules to stick together and the gas becomes a liquid
-Molecules of a real gas are more like “soft” spheres. Shape change during collision and rebound makes this process occur a little more slowly. This means that the pressure of the gas is actually a little less than ideal.
Conversions
101.325kpa/1 atm/ 760mmHG
Celsius to kelvin?
+273.15
Kelvin to Celsius?
-273.15
