Module 3: Macroscopic Systems Flashcards
(83 cards)
0
Q
How much is a mole?
A
6.0 e 23 atoms
1
Q
How much is a mole in terms of hydrogen?
A
One gram of H is one mole of H
2
Q
What is the name for the number of atoms in a mole?
A
Avogadro’s number
3
Q
What do scientists now use to measure moles?
A
Carbon
4
Q
How much is a mole in terms of carbon?
A
One mole is the number of atoms in 12.0000 grams of carbon.
5
Q
What is the more precise Avogadro’s number?
A
6.0221415 e 23 1/mol
6
Q
If you know the number of particles…?
A
Divide by Avogadro’s number to get the number of moles
7
Q
If you know the number of moles….
A
Multiply by Avogadro’s number to get the number of particles
8
Q
What was the basis for Avogadro’s principle?
A
At the same temperature and pressure, equal volumes of all gases have the same number of molecules.
9
Q
Molar mass has phased out what term?
A
Molecular weight
10
Q
If you know the number of moles of a substance, how do you find the substance’s mass?
A
Multiply by the molar mass
11
Q
1 mol of A2B3 : how many moles of A and B?
A
Two and three
12
Q
Let’s say we have 3 moles of compound A 2 B 3 and someone wants to know how many atoms of B are there?
A
33 Avogadro’s number =number of atoms
13
Q
How does one find molar masses of elements?
A
Look at the periodic table
14
Q
A beaker contains 18 g of water.
a. How many moles of water are there?
A
(2 mol H) (1 g/mol) + (1 mol O) (16 g/mol) = 18g/mol molar mass of water
18g/ (18 g/mol) = 1 mol
15
Q
A beaker contains 18 g of water.
b. How many molecules are in the beaker?
A
1 mol * 6.022e23 = 6.022e23
16
Q
What is the largest component of air?
A
Nitrogen
17
Q
What factors determine the state of a gas?
A
Temperature, volume, pressure
18
Q
What is the third law of thermodynamics?
A
There is a coldest temperature below which no other temperature can exist
19
Q
Water melts at?
A
273.15 K
20
Q
Water boils at?
A
373.15 K
21
Q
A change of 1K is the same as a change of what?
A
1 *C
22
Q
What is the formula for pressure?
A
Force/Area
23
Q
Unit for pressure
A
Pascals
24
Boyle's law
Inverse relationship between volume and pressure
VP= k
25
Charles' law
Gas volume is directly proportional to temperature
V=bT
26
Avogadro's law
At a constant temp and pressure, the volume of a gas is directly proportional to the number of moles of the gas
27
What is the ideal gas law?
PV=nRT
N =number of moles of the gas
R = constant
28
What is r?
Gas constant
8. 134 J/mol K
0. 08206 L atm/ mol K
29
Two assumptions of the ideal gas law
the volume of individual gas atoms is negligible
| the gas particles do not have attractive forces between them
30
To use the law with SI units of Volume in m 3, the pressure should be in?
Pascals or N/m 2, and the R constant is in 8.31 J/Kelvin mol, temperature in Kelvin
31
With non SI units, the gas constant R will have a value of?
0.08206 L atm/K mol, the volume should be in Liters, and the pressure in atmospheres. The temperature is always in Kelvin.
32
One mol of an idea gas is what volume?
22.4 L
33
What is STP?
standard conditions of temperature and pressure or STP, or a temperature of 0 o C or 273.15 K and pressure of 1 atm
34
What is molarity?
The ratio of n to volume in liters
35
What is the formula for molar mass?
dRT/P= molar mass
36
What does Dalton's law say?
the total pressure of the gas is then exactly the sum of all the partial pressures
37
What is the mole fraction?
The number of moles of one component divided by the total number of moles in the entire mixture
38
What two equations modify the ideal gas law?
The virial equation and the van der Waals equation of state
39
What the kinetic theory of gases?
a model that envisions gases to be largely empty space, punctuated by small molecules that move in any direction at a very large speed
40
What is the formula for average velocity of a molecule?
v avg = sqrt(8RT/pi m)
41
What doe liquids have that gases don't?
Surfaces
42
Why do liquid droplets often form a sphere?
To reduce surface area: more surface molecules means more surface tension pulling the molecules toward the center, thus a higher energy. Less surface area means lower energy.
43
What is a solution?
A phase where particles mix on an atomic or molecular level
44
What is the general rule of thumb for solvation?
Like dissolves like
45
During dissolution of molecular compounds, what happens?
Molecules of the solvent surround the molecules of the solute
46
What happens during ionic dissolution?
The solvent breaks apart the molecules of the solute.
47
Why is it energetically favorable for water molecules to break apart ionic compounds such as NaCl?
The positive hydrogen regions of the water molecules are attracted to the negative Cl ions, and the positive charge partially deionizes the Cl, which brings the overall energy down, and thus is energetically favorable
48
Solutions where ions a completely separate create strong what?
Electrolytes
49
What is a nonelectrolyte?
A molecule that provides the solution with no ions and thus no capability to conduct electricity well
50
What are three examples of strong electrolytes?
Neutral salts, strong acids, and strong bases
51
Why does hydrochloride acid ionize completely in water even thou it is a molecular compound?
There is such an electronegativity difference between H and Cl, so the Cl becomes an ion.
52
What are the six most common strong acids?
HBr, HI, HCl, H2SO4, HClO4, HNO3
53
What are examples of strong bases?
Soluble metal hydroxides like NaOH and KOH
54
Why are sparingly soluble crystalline substances like AgCl weak electrolytes?
They don't like to dissociate and ionize, so only a little bit of the compound ionizes.
55
Why are some molecules weak acids?
they only partially ionize by reaction with water. The water behaves as the base in the reaction with a weak acid
56
Why are nitrogen-containing bases weak electrolytes?
water is behaving as the acid because it is donating a proton to the weak base, so the compound not partially ionizes
57
What is the formula for molarity?
Moles of solute/ liters of solution in mol/L
58
How does one easily make a 0.1 M solution?
Take 0.1 mol of the solute, dissolve it in the solvent, then add enough solvent to be 1 L
59
Describe how to prepare 1L of 1 M solution of HCl from conc. HCl (11.6 M).
VM= mol, and we need one mol, so V*11.6 mol/L=1 mol, so divide 1 mol/11.6 mol/L = 0.0862 L
60
What is the dilution equation?
M1V1 = M2V2
61
Why does molarity depend on temperature?
So does volume
62
What is the formula for molality?
Moles of solute/kg of solvent in mol/kg
63
Because molality refers only to ?, it doesn't depend on ?
Mass, temperature
64
Why are the molarity and molality of water similar?
The volume doesn't change much when salutes are dissolved, and because water weighs 1 kg per liter.
65
Is the pressure of water vapor at room temperature small or large?
Small
66
Every solid technically has a vapor pressure of what?
Near zero
67
What is the vapor pressure of water?
.02 bar
68
Does water vapor care about the presence or absence of air?
No: when you open the half and half water and water vapor container, air rushes in but only at .98 pressure because the other .02 is water vapor pressure
69
What happens on a slower scale when the half and half water vapor and water container is opened?
Water vapor starts to diffuse it of the container; the liquid water tries to compensate so it evaporates more of itself into water vapor; etc until all water has evaporated into water vapor and all water vapor has diffused into the surrounding air
70
What happens to vapor pressure as temperature rises?
Vapor pressure rises
71
What is a phase diagram?
A diagram that shows the dependence of pressure on temperature for a certain substance
72
What is SATP?
Standard ambient temperature and pressure
73
What happens when the water vapor pressure gets to the ambient 1 bar of pressure?
It cannot exceed 1 bar, s it forms water vapor bubbles and escapes as a gas, aka boils.
74
Why does water boil at 100*C?
Because on the phase diagram, water changes phase from liquid to gas when the water vapor pressure is equal to the ambient pressure of 1 bar, which lines up with 100*C
75
How do pressure cookers work?
The pressure increases, and on the phase diagram that increases temperature
76
What is solubility?
The limit to the number of ions that can be dissolved in water; a property of the ionic compound being dissolved in water
77
What is the solubility product constant?
Ksp, the maximum concentration of ions in a solution in moles per L, determined by multiplying the concentrations of the ions in the solution
78
What is the equilibrium constant?
the product of the concentrations of all the concentrations of products and reactants involved, each to the power of the coefficients in the balanced equation
79
What two concentrations do not factor not equilibrium constants?
Of pure solids and pure liquids
80
What is the 'common ion' solubility product problem?
When one dissolved an ionic compound in a solution that already contains a concentration of one of the ions of the original ionic compound
81
What should me use to solve solubility equilbria problems?
An ICE table
82
In general, solubility products are dependent on what?
Temperature
