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General Chemistry > exam 3 > Flashcards

exam 3 Flashcards

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1
Q

Molarity

A

the moles of solute per liter of solution.

M: mol/Liter

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2
Q

what is the molality of a solution where 333 of KHCO3 is dissolved in enough water to make 10 L of solution?

A
  1. Convert g of KHCO to moles of HCO3
    (333g KHCO3) x (1 mole KHCO3/100.1 g KHCO3) : 3.33 mol
  2. Use this value as the numerator in the defining equation for molarity
    3.33 mol/10L: 0.333 M KHCO3
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3
Q

what mass in g of NaCl is requires to prepare 0.5 : of typical over the counter saline solution (0.15 M NaCl)?

A
  1. Use molality as a conversion factor to calculate mole of NaCl
    (0. 5 L) x (0.15 mol NaCl/1 L solution): 0.075 mol NaCl
  2. Use the molar mass to calculate g of NaCl
    (0. 075 mol NaCl)x(58.5 g NaCl/1 mol NaCl): 44 g
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4
Q

Concentrated HCl is 12.0 M HCl. what volume in mL of this solution contains 0.425 mol HCl?

A
  1. Use the molality as a conversion factor to calculate mols of
    moles of solute/molality: 0.425 mol HCl/12.0 M HCl
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5
Q

Concentrated HCl is 12.0 M HCl. what volume in mL of this solution contains 0.425 mol HCl?

A
  1. Use the molarity as a conversion factor to calculate mols of
    moles of solute/molality: 0.425 mol HCl/12.0 M HCl: 0.0354 L
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6
Q

Percent concentration by volume

A

volume of solute/volume of solution (100%)

ex: (120 ml of oil/4000 ml of solution) x 100%: 30%

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7
Q

Percent concentration by mass

A

mass of solute/mass of solution (100%)
Ex: what is the % by mass of NaCl if 25.5 g of it is dissolved in 425 g of water?
25.5 g NaCl/(25.5g+425g) x100%: 5.66%

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8
Q

Ionic bonds

A

strongest force that holds matter in the condensed state.
electronegativity differences determine whether compounds contain polar or non polar covalent bonds in molecular compounds or ionic bonds in ionic compounds.

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9
Q

INTRAMOLECULAR forces action

A

keep the elements together in their molecules

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10
Q

INTERMOLECULAR forces action

A

between molecules. Determines how molecular compounds interact with each other.

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11
Q

intermolecular forces

DIPOLES

A

the separation of the charges in the molecules such as in the ionic bond or the unequal sharing of the electrons such as in the polar covalent bonds.

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12
Q

Dipole forces

A

polar molecules exist as dipoles. These oppositely charged ends will attract each other

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13
Q

Hydrogen bonds

A

when a hydrogen atoms is covalently bonded to a highly electronegative atoms like nitrogen, oxygen or fluorine, it can exhibit an additional polar attraction

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14
Q

Dispersion Forces

A

nonpolar molecules exhibit a dynamic weak induced dipole due to continuos movement of the electrons. The strength of the forces increases with molecular weight. The resulting dipole attractions are called cores or LONDON DISPERSION FORCES. They can exist between any 2 particles whether polar, non polar or ionic.

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15
Q

Types of intermolecular forces

A

dipole to dipole (ionic and polar covalent molecules)
hydrogen bond forces (molecules with hydrogen and high electronegativity elements >0.5)
dispersion forces (ionic, polar

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16
Q

Types of intermolecular forces

A

dipole to dipole (ionic and polar covalent molecules)
hydrogen bond forces (molecules with hydrogen and high electronegativity elements >0.5)
dispersion forces (ionic, polar)

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17
Q

solution

A

a homogeneous mixture of 2 or more substances

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18
Q

solute

A

a substance that is dispersed in a solution

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19
Q

solvent

A

the substance doing the dissolving. Present in greatest quantity

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20
Q

Like dissolves like

A

solutions from most readily when both the solute and solvent have similar intermolecular forces.

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21
Q

ionic substances

A

dissolve in water through ion dipole interactions. In non polar solvents there are basically no dipole forces that can attract the ionic substances and therefore break it apart (dissolve)

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22
Q

solvent: ionic
solute: polar covalent

A

solute will dissolve in solvent

23
Q

Kinetic molecular theory of a gas

A
  1. particles of a gas are in rapid constant motion
  2. The gas particles are tiny compared to the distance between them
  3. there is little attraction between the particles of a gas
  4. collisions between gas molecules are perfectly elastic
  5. temperature is a measure of the average kinetic energy of a gas molecule.
24
Q

Boyle’s law

A

At a constant temp, the volume of a gas is inversely proportional to its pressure,
V1P1: V2P2

25
Q

Charle’s law

A

At a constant pressure, the volume of a gas is directly proportional to its absolute temperature.
V1/T1: V2/T2

26
Q

Avogadro’s law

A

at a fixed temperature and pressure, the volume of a gas is directly proportional to the amount of gas.
v1/n1: V2/n2
a mole of any gas occupies 22.4L @ STP

27
Q

Calculate the density of a nitrogen gas and methane gas, both at STP

A

28g N2/1 moleN2 x 1 mole N2/22.4 LN2: 1.25g/L

  1. g CH4/1 mole CH4 x 1 mole CH4/22/4 LCH4: 0.714 g/L
28
Q

combined gas law

A

P1V1/T1: P2V2/T2

29
Q

Ideal gas Law

A

PV: nRT
R: 0.0821 L atm/mol (K)
n: moles

30
Q

Ideal gas Law

A

PV: nRT
R: 0.0821 L atm/mol (K)
n: moles

31
Q

Blue Litmus paper turns

A

red in acid

32
Q

Red litmus paper turns

A

blue in alkaline

33
Q

A base and an acid form (NaOH+HCl)

A

water and salt

34
Q

Acids

A

molecular substance that ionizes in aqueous solution to produce hydrogen ions (H+)

35
Q

Bases

A

a substance that produce hydroxide ions (OH-)

36
Q

HNO3 forms

A

H+ (aq) + NO3 (aq_

37
Q

KOH forms

A

K+ (aq) + OH- (aq)

38
Q

Neutralization

A

when an acid reacts with a base, the properties of each are neutralized and the products are water and salt.

39
Q

Limitations of the Arrhenius theory

A

H+ ions don’t exist in water solution. Protons react with water to form hydronium ions (H30)
H++H20—>H30
-doesnt explain the basicity of ammonia and similar compounds.
-it only applies to reactions in aqueous solutions

40
Q

Bronted Lowry Theory

A

Acid: proton donor
HCl + H20—> H30++Cl-
Base: proton acceptor
NH3 + H20—>NH4++ OH-

41
Q

Salts

A

ionic compunds composed of cations other than hydrogen and anions other than hydroxide ( AgNO3, SnF2, etc)

42
Q

anhydride

A

means without water
nonmetal oxides are acidic anhydrides
nonmetal oxides + water: acid
ex: SiO+H20: H2SiO2

43
Q

metal oxides

A

are basic anhydrides
metal oxides+H20: base
ex: MgO+H20: Mg (OH)2

44
Q

strong acids

A

ionize completely in water solution

less than 2

45
Q

weak acid

A

only partially ionize in water solution

46
Q

strong bases

A

ionize or dissociate completely in water solution

more than 12

47
Q

Weak bases

A

only partially ionize in water solution

48
Q

why is ammonia a base?

A

because it accepts a proton from water

49
Q

the amount of acid or base in a solution is determined by

A

careful neutralization

50
Q

concentration of H+

A

1x10-0: pH of 0

1x10-6: pH of 6

51
Q

conjugate base

A

the Cl- from

HCl—> H++ Cl-

52
Q

conjugate acid

A

anything that is not OH-

53
Q

Buffer solutions

A

contain a weak acid and its conjugate base.

Capable of maintaining a nearly constant pH when small amount of acid or base are added.

General Chemistry (3 decks)

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