General Chemistry- The Gas Phase Flashcards Preview

My MCAT Study > General Chemistry- The Gas Phase > Flashcards

Flashcards in General Chemistry- The Gas Phase Deck (87)
Loading flashcards...
1

What are the three different physical forms matter can exist as?

Gas
Liquid
Solid

2

What are the general names for the different physical forms of matter?

Phases or states

3

How are gases classified? Why? Why are they different from liquids?

Classified as fluids because they can flow and take on the shapes of their containers. However, the atoms or molecules in a gaseous sample move rapidly and are far apart from each other.

4

What is weak in gas molecules? What does this result in?

Intermolecular forces.
Results in certain characteristic physical properties, such as the ability to expand to fill any volume. Gases are also easily compressible, which distinguishes them from liquids.

5

How can you define the state of a gaseous sample, what 4 factors?

Pressure (P)
Volume (V)
Temperature (T)
Number of moles (n)

6

What units are used for pressure?

1 atm= 760 mmHg= 760 torr= 101.325 kPa

7

How does a barometer work?

Atmospheric pressure creates a downward force on the pool of mercury at the base of the barometer while the mercury in the column exerts an opposing force (its weight) based on its density. The weight of the mercury creates a vacuum in the top of the tube. When the external air exerts a lower force than the weight of the mercury, the column falls.

8

What units are used for volume of gas?

liters (L)
milliliters (mL)

9

What units is temperature usually expressed in?

Kelvins (K)
Although Celsius (C) may be used

10

Many processes involving gas take place under which conditions?

Standard temperature and pressure (STP) which refers to 273 K (0 degrees celsius)

11

Is STP conditions the same as standard state conditions?

No

12

When are STP or SSC used?

STP (273 K and 1 atm) is generally used for gas law calculations; standard state conditions (298 K, 1 atm, 1 M concentrations) are used when measuring standard enthalpy, entropy, free energy changes, and electrochemical cell voltage.

13

What is an ideal gas?

A hypothetical gas with molecules that have no intermolecular forces and occupy no volume.

14

How are real gases the same or different from ideal gases?

Real gases deviate from this ideal behavior at high pressures (low volumes) and low temperatures, many compressed real gases demonstrate behavior that is close to ideal.

15

Who discovered the ideal gas law, when?

Benoit Paul Emile Clapeyron (1834)

16

What laws were discovered before the ideal gas law?

Boyle's law, charle's law, and dalton's law

17

What is the ideal gas law equation?

PV= nRT

18

What do the letters represent in the ideal gas law equation?

P: pressure
V: volume
n: Number of moles
T: temperature
R: The ideal gas constant (8.21X10^-2 L (atm)/mol K) or (8.314 J/K mol)

19

Will the values for the ideal gas constant be provided on test day?

Yes

20

Why is the ideal gas law used?

To determine the missing term when given all of the others. It can also be used to calculate the change in a term while holding two of the others constant. It is most commonly used to solve for volume or pressure at any given temperature and number of moles.

21

The ideal gas law is also used to determine what?

Gas density and molar mass

22

How do you define density?

(p) as the ratio of the mass per unit volume of a substance

23

What units are usually used for density of a gas?

Grams per liter

24

How many liters is ideal gas at STP?

22.4L

25

When is the combined gas law used?

To relate changes in temperature, volume, and pressure of a gas.

26

What is the combined gas law equation?

P1V1/T1 = P2V2/T2

27

What do the units represent in the combined gas law equation?

The subscripts 1 and 2 refer to the two states of the gas (at STP and at the conditions of actual temperature and pressure, for example).

28

What is assumed stable in the combined gas law?

Number of moles

29

How do you calculate a change in volume using the combined gas law?

V2= V1 [P1/P2] [T2/T1]

30

How do you find the density of gas under nonstandard conditions after finding the volume change in gas?

V2 is then used to find the density of the gas under nonstandard conditions.
p= m/V2