Chem Ch 11 and Cumulative Final

Entropy and spontaneity

+∆S is favorable for spontaneity (more disorder) -∆S is unfavorable for spontaneity (less disorder)

How many kcal are released if 2.50 moles of H₂ reacted? N₂ + 3H₂ → 2NH₃

-19.2 kcal

Calculate enthalpy in kcal for N₂ + 3H₂ → 2NH₃ (hint: use bond dissociation energy table)

-23 kcal

How many kcal are released when 3.50 moles of N₂ react? N₂ + 3H₂ → 2NH₃

-80.5 kcal

Oxidation Number Rules

-atom in elemental state as ON of 0 -monatomic ion has ON = to its charge -binary ionic compound, ON = charge -covalent compound, atom usually has same ON as if it were monatomic --- More EN atom gets negative ON, less EN atoms get positive ONs, O is almost always 2-, H is almost always 1+ -sum of ON in neutral compound is 0, in polyatomic, it is equal to charge

How many unpaired and valence electrons in mercury

0 unpaired and 2 valence

132.0 m to km

0.1320km

Air in the trachea contains oxygen, carbon dioxide, water, and nitrogen. If the total pressure is 1.000 atm and that partial pressure of CO₂ is 0.004atm, the partial pressure of H₂O is 0.062atm, and the partial pressure of N₂ is 0.740atm, what is the partial presssure of O₂? What percentage of the gas is O₂?

0.194atm 19.4%

What is the specific heat of a metal if it takes 161 cal to raise the temperature of a 75.0 g piece by 10.0°C?

0.215 cal/J

Pressure Conversions

1 atm = 760 mm Hg = 760 torr = 14.7 psi 1 atm = 29.9 in Hg = 101,325 Pa = 101.325 kPa

1 cc (cm³) is equal to

1 mL

How many orbitals in each shell (s, p, d, and f)

1, 3, 5, and 7 respectively

1 kj = how many joules?

1,000 J

1 kcal = how many cal?

1,000 cal

WO₃ + 3H₂ → W + 3H₂O 1. How many grams of water could be made from 50.0g of WO₃? 2. How many grams of water could be made from 50.0g of H₂?

1. 11.7g 2. 447g

CH₄ + 2O₂ → 2H₂O + CO₂ 1. How many grams of CO₂ can be made from 5.00 moles of O₂? 2. How many molecules of H₂O could be made from 3.50 moles of CH₄? 3. How many moles of CH₄ are required to react with 56.0 grams of O₂

1. 110. g 2. 4.22x10²⁴ 3. 0.875 mol

Steps for assigning Oxidation numbers in binary compounds (2 elements)

1. Assign most electronegative element first; ON = negative ion charge 2. Less Electronegative element has positive ON to balance out so that total oxidation numbers equals compound's charge

Steps for assigning Oxidation numbers in non-binary compounds (more than 2 elements)

1. Assign the most EN element the negative ON equal to its ion charge 2. Assign least EN element positive ON equal to its ion chare 3. The elements with mid-EN values take ON to balance out so that total equals compound's charge

Two ways to determine whether a change of state occurs spontaneously at a given T

1. Calculate ∆G, if negative -- spontaneous, if positive -- nonspontaneous 2. Look at the temperature the change of state happens at and determine if it is above or below the temperature required

Steps to draw Lewis Structure

1. Decide the bonding pattern of molecule - Put atom with most bonds/you have fewer of in center 2. Add up total number of valence electrons available from all atoms in molecule -If positive charge, subtract those electrons -If negative charge, add those electrons 3. Draw a line (or place 2 dots) between each pair of connected atoms 4. Add lone pairs of electrons to each peripheral atom until each has octet *H only needs 1 bond, B only needs 3 5. Place any remaining electrons as lone pairs on center atom 6. If center atoms lacks octet, take lone pair from surrounding atom and make it a bonding pair to form a multiple bond

WO₃ + 3H₂ → W + 3H₂O 1. If you react 50.0 g of WO₃ and 50.0 g of H₂, what is limiting reagent? 2. What is the theoretical yield of water when reacting 50.0 g of WO₃ and 50.0 g of H₂? 3. If the reaction was done using 50.0 g of WO₃ and 50.0 g of H₂and only produced 10.0 g of water, what is the percent yield? 4. How many grams of excess reagent will be left over if theoretical yield of water is achieved? **11.7g water made from 50.0 g WO₃ and 447 g water made from H₂O**

1. WO₃ 2. 11.6 g 3. 86.2% 4. 48.72 g

Steps for balancing chemical equations

1. Write unbalanced equation with charge-balanced ionic compounds or prefixes for covalent compounds and remember diatomic elements 2. Add coefficients to balance atom numbers on each side - treat polyatomic ions as single unit if they appear on both sides 3. Reduce coefficients to lowest whole-number values

1,500,000 g to Mg

1.5 Mg

1 Mile to m

1.609 m

How many moles of H₂ are needed to react with 3.50 moles of N₂

10.5 mol

1 cubic meter to liters

1000 L

Femto f

10^-15

Hecto h

10²

Kilo k

10³

Deka da

10¹

Mega M

10⁶

Centi c

10⁻²

Milli m

10⁻³

Deci d

10⁻¹

Micro µ

10⁻⁶

Nano n

10⁻⁹

Pico p

10∧-12

How many kcal are released if 17.0 g of NH₃ is made? N₂ + 3H₂ → 2NH₃

11.5 kcal

Carbon has three naturally occurring isotopes, 98.88% is C-12 and 1.10% is C-13 and 0.02% is C-14. Calculate the atomic weight (in amu) for carbon to 4 sig figs

12.01 amu

2,550 fl oz to gal

19.9 gal

Iodine Electron Configuration

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d10,5p⁵ Or [Kr]6s²4d¹⁰5p⁵

Linear Molecular Geometry

2 Bonded atoms, 0 lone pairs, 2 total charge clouds, 180° angles

Bent Molecular Geometry (3 charge clouds)

2 bonded atoms, 1 lone pair, 3 charge clouds, 120° angles

Bent Molecular Geometry (4 charge clouds)

2 bonded atoms, 2 lone pairs, 4 charge clouds, 109° angles

sulfur valence electrons and unpaired electrons

2 unpaired, 6 valence

1 kg to lb

2.205 lb

1 Inch to cm

2.54 cm

What is the density of a metal piece with a mass of 23,000 mg and volume of 0.00856 L in g/mL? Will it float or sink in water?

2.9 g/ml, it will sink

What is mass of a copper penny if it contains 2.94x10²² atoms of copper - round to 3sf

2.94x10²²

2.00 x 10∧10 bytes to GB

20.0 GB

2.040 x 10⁻² g to mg

20.40mg

How much energy would be required to change 25 g of liquid ether at 20.6°C into gaseous ether at 38.6°C? The specific heat of liquid ether is 0.55 cal/g°C; the specific heat of ether vapor is 0.38 cal/g°C.

2400 cal total

Trigonal Planar Molecular Geometry

3 bonded atoms, 0 lone pairs, 3 charge clouds, 120° angles

Pyramidal Molecular Geometry

3 bonded atoms, 1 lone pair, 4 charge clouds, 109° angles

1 Foot to cm

30.48 cm

Tetrahedral Molecular Geometry

4 bonded atoms, 0 lone pairs, 4 charge clouds, 109° angles

1 cal = how many joules?

4.184 J

1 kcal = how many kj

4.184 kJ

150 g of iron is at an initial temperature of 25° C. If 250 cal of energy is applied to the sample, what is the final temperature?

41°C

In an experiment, 2SO₂ + O₂ ↔ 2SO₃ at equilibrium had SO₃ concentration of 0.938M, an SO₂ concentration of 0.0620M and O₂ concentration of 0.538M, what is the equilibrium constant?

425

0.00045 L to µL

450 µ or 4.5 x 10²µ

Calculate the mass in grams of 0.500 quarts of blood with density of 103 g/ml

487 g

Calculate the volume of 50.0 g of ice with density 0.917 g/cc in mL

54.5 mL

A patient weighing 143 pounds has a prescription for Garamycin at two mg/kg, to be given by IV, every 8 hours. The drug is available in vials containing 100mg Garamycin per 50mL. How many milliliters should the nurse administer to the patient with each 8-hour dose?

64.9mL per 8 hour dose

255,000 cc to gal

67.4 gal

What is the mass (g) of 2.25 fl. oz. of liquid with a specific gravity of 1.12?

74.5 g

Which of the following have increased entropy? A. Dry ice changing from solid to gas B. Freezing liquid water to make ice C. N₂(g) + 3H₂(g) → 2NH₃(g) D. CaCO₃(s) → CaO(s) + CO₂(g) E. Dissolving sugar into water to make a sugar-water solution

A -- gas has more disorder than solid D -- 2 moles of product and 1 mole of reactant, also, gas is more disordered E -- sugar molecules become more spread out

Select all that would be classified as exothermic A. 2H₂O₂ → 2H₂O + O₂ + 48 kcal B. ∆H = +26 kcal C. 2N₂O₅ + 110 kj → 4NO₂ + O₂ D. ∆H = -424 kJ E. boiling water F. Freezing liquid water into ice G. Forming a bond H. Breaking a bond

A, D, F, and G

Group 1A (periodic table) name and characteristics

Alkali Metals, Shiny, soft metals with low melting points, react rapidly with water to form highly alkaline (basic) products, Never found in nature in pure state

Group 2A (periodic table) name and characteristics

Alkaline Earth Metals, Lustrous, silvery metals but less reactive than group 1A, Never found in nature in pure state

What is required for molecule to be symmetric?

All electron cloud regions surrounding all central atoms must be identical -- symmetric molecules never have lone pairs

Metalloids Characteristics

Along zigzag band between metals and nonmetals, share some characteristics of both metals and nonmetals

Aluminum and Oxygen Name and Equation

Aluminum Oxide Al₂O₃

Compounds

Atoms of different elements combined in specific ratio Chemical formula indicates what elements and how many atoms Can be broken into elements through chemical change

If you add a substance, which way will equilibrium shift?

Away from the side where it was added

Diatomic elements and meaning

Br, I, N, Cl, H, O, F --- always 2 when they are alone

Name BrCl₅

Bromine pentachloride

Fahrenheit to Celsius

C = (F-32)/1.8

Kelvin to Celsius

C = K - 273.15

Acetate

CH₃COO¹⁻

Cyanide

CN¹⁻

Carbonate

CO₃²⁻

Calcium and Fluorine Name and Equation

Calcium Fluoride CaF₂

Which of these (select all) would likely form a cation? 1. Calcium 2. Cesium 3. Copper 4. Bromine 5. Neon 6. Aluminum

Calcium, Cesium, Copper, and Aluminum

Assign oxidation numbers to each element, Identify oxidized element, reduced element, oxidizing agent, and reducing agent C₂H₄ (l) + KMnO₄ (aq) → CH₃COOH(aq) +MnO₂(s) + K⁺(aq)

Carbon is oxidized Manganese is reduced C₂H₄ is reducing agent KMnO₄ is oxidizing agent

Line structures

Carbons are wherever line begins or ends and at every intersection of 2 lines; hydrogen atoms are wherever they are needed so each carbon has 4 bonds, lone pairs not shown, HONC 1234 used

What is an ion

Charged particle resulting from the gain or loss of electrons from an atom

Apple Ripening Physical or Chemical?

Chemical

Changes chemical makeup of substance Physical or Chemical?

Chemical

Making water from Hydrogen and Oxygen Physical or Chemical?

Chemical

Often accompanied by indication such as color change or heat absorbed/gave off Physical or Chemical?

Chemical

Often not easily reversible Physical or Chemical?

Chemical

When a chemical bond is broken, what type of change occurs?

Chemical

Intramolecular forces

Chemical bonds like ionic bonds and Covalent bonds

Chlorate

ClO₃¹⁻

Group (periodic table)

Column

Propane Element, compound, homogeneous, or heterogeneous

Compound

Cu⁺ ion name

Copper (I)

Which has a lower melting point, covalent or ionic substance?

Covalent

Chromate

CrO₄²⁻

Dichromate

Cr₂O₇²⁻

Density Equation

Density = Mass/Volume

Naming negative ion

Dropping ending from element name and adding -ide

Valence electrons

Electrons in the outermost shell (furthest from the nucleus)

Tungsten Wedding Band Element, compound, homogeneous, or heterogeneous

Element

Isotope Symbol and Name

Element Name - Mass #

Two types of pure substances

Elements and Compounds

Melting, boiling, and sublimation (solid to gas) are endothermic or exothermic?

Endothermic

When a substance is at its phase change temperature, heat is used to overcome the intermolecular forces holding particles in that phase. The temperature remains constant until all particles have been converted Two equations for this are...

Energy = mass * heat of fusion (for melting/freezing) Energy = mass * heat of vaporization (for boiling/condensing)

Bond Dissociation Energry

Energy required to break a chemical bond

Energy (heat) equation

Energy(heat) = mass*specific heat*temperature change or q=mC∆T (∆T is final-initial temp)

Ionic equation

Equation in which dissociated ions are explicitly shown (aqueous ionic compounds dissociate) Pb²⁺ (aq) + 2NO₃⁻ (aq) + 2Na⁺ (aq) + 2I⁻ (aq) → PbI₂ (s) + 2Na⁺ (aq) + 2NO₃⁻ (aq)

Intermolecular forces

Exist between atoms and molecules, determining their physical properties; solubility, boiling points, and melting points. They are caused by the attractions between atoms or molecules due to the presence of full or partial charges caused by the unequal distribution of electrons

Freezing, condensing (gas to liqud) and deposition (gas to solid) are endothermic or exothermic?

Exothermic

Celsius to Farhenheit

F = (1.8 * C) + 32

Does something with a smaller specific heat heat up faster or slower?

Faster

What type of ions do transition elements for and how do you name them?

Form positive ions with variable charges so use roman numeral after name to indicate charge on specific ion -- except Ag is always 1+ and Zn is always 2+

Smallest unit of ionic compound

Formula Unit

Chemical formula vs Name

Formula is symbols and subscripts, name is written out words

Elements

Found on periodic table Cannot be broken down into anything simpler

How do nonmetals form ions

Gain electrons to have 8 valence electrons and for positive ions

London Dispersion Forces

Get stronger as size (or number of electrongs) increases; results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles

What cation will acids have?

H+

Bicarbonate

HCO₃¹⁻

Group 7A (periodic table) name and characteristics

Halogens, Colorful and corrosive nonmetals, found in nature in combination with other elements, halogen from greek word meaning salt

Shaker filled with cinnamon sugar Element, compound, homogeneous, or heterogeneous

Heterogeneous

Do polar molecules experience a higher or lower boiling point than nonpolar molecules?

Higher -- stronger IMF

Gasoline Element, compound, homogeneous, or heterogeneous

Homogeneous

Two Types of Mixtures

Homogeneous and heterogeneous

Difference between homogeneous and heterogeneous

Homogeneous is uniform Heterogeneous is not uniform

HONC 1234 meaning

Hydrogen, oxygen, nitrogen, and carbon make 1, 2, 3, and 4 bonds respectively

Where are ionic bonds found?

In ionic compounds

A child weighing 30 kg arrives at the clinic with diffuse itching as the result of an allergic reaction to an insect bite. The doctor prescribes 25 mg of benedryl to be taken 3 times a day. The correct pediatric does is 5 mg/kg/day. Is the prescribed correct? If not, what is the correct dose (at 3 times) per day?

Incorrect, Need 50 mg/dose

Lanthanides and Actinides (periodic table)

Inner Transition Metals (2 rows at botton of table)

How to name bases

Ionic compound naming rules

Differences between ionic bonds and covalent bonds

Ionic: Depends on ionization energy, electron affinity, and electron configurations Covalent: Depends on electron configuration and differences in electronegativities

Differences between ionic compounds and molecular compounds

Ionic: balance charges of cations and anions, soluble in polar solvents, high melting points, solution conductivity Covalent/Molecular: represented by lewis structures, polar or nonpolar, low melting and boiling points

Does an item float or sink if its density is greater than water's?

It sinks

Equilibrium Constant

K -- indicates the positions of the reaction at equilibrium and calculated by plugging in concentrations of reactants and products at equilibrium into equilibrium equation

Celsius to Kelvin

K = C + 273.15

Is the energy required to break an intermolecular force greater than or less than the energy required to break a chemical bond?

Less than

Ionic name Lithium

Lithium ion

How do main group metals form ions

Lose Valence electrons and form positive ions (Main group elements in same group for same ion charge)

If atmospheric pressure is lower, will the boiling temperature be higher or lower?

Lower

Group A (periodic table)

Main Group Elements

Air Element, compound, homogeneous, or heterogeneous

Mixture - debatable on what type

Permanganate

MnO₄¹⁻

Hydrogen Bond IMF

Moderate Strength (2-10kcal/mol, 8-40kJ/mol); occurs between molecules with O-H, N-H, and/or F-H bonds

More unequally electrons shared: more or less polar bond?

More polar

Ammonium

NH₄¹⁺

Nitrate

NO₃¹⁻

Naming Positive Ions

Named with name of element and word ion

Dipole CH₂O

Net dipole toward O

Zero at beginning of decimal number Significant?

No

Zero used as placeholder in large number with no decimal point Significant?

No

Group 8A (periodic table) name and characteristics

Noble Gases, Colorless gases, lack chemical reactivity

If dipoles cancel, is molecule polar or nonpolar

Nonpolar (if they do not, it is polar)

Drawing Orbital Diagrams

Number of boxes = number of orbitals, fill each with one first, then fill with rest of electrons

Unpaired Electrons

Number of electrons not paired up in orbitals

Atomic Number

Number of protons (and electrons)

How to determine unpaired electrons

Number of single electrons in orbital diagram

What does group number of main group elements tell you about valence electrons?

Number of valence electrons

HPO₄²⁻ Oxidation Numbers

O = -2 H = +1 P = +5

N₂O₅ Oxidation Numbers

O= -2 N= +5

Hypochlorite

OCl¹⁻

What ion do bases have?

OH-

Hydroxide

OH¹⁻

Phosphate

PO₄³⁻

Pa Equation

Pa = moles A/total moles (or %A) * total pressure %A = Pa/Ptotal * 100

H-bond acceptor

Partial negative F, O, or N bonded to H

H-bond donor

Partial positive bonded to F, O, or N

Ionic name Phosphorus

Phosphide

Changes of state or particle size Physical or Chemical?

Physical

Dissolving salt in water Physical or Chemical?

Physical

Does not alter chemical makeup of substance Physical or Chemical?

Physical

Grinding Metal Physical or Chemical?

Physical

Often are easily reversible Physical or Chemical?

Physical

When intermolecular forces are broken, is it a physical or chemical change?

Physical

How to tell difference between precipitation, neutralization, and redox

Precipitation: has aqueous parts with a solid in products Neutralization: has acid/base Redox: typically has element alone

Mass #

Protons + Neutrons

What to do if polyatomic ion needs subscript in ionic compound?

Put polyatomic ion in parentheses and add subscript outside of it

Boyle's Law

P₁V₁=P₂V₂

Formula for Tetraphosphorus decaoxide

P₄O₁₀

What does a balanced equation tell us?

Relative amounts of product and reactants (moles can also be inferred in stoich problems)

Period (periodic table)

Row

Sulfate

SO₄²⁻

What determines the strength of IMF for non-polar molecules?

Size of the molecule (or # of electrons), larger molecule = stronger IMF

Atomic Radius trend

Smaller to right of periodic table

Acetic acid has melting point of 16.7°C and boiling point of 118°C. What state of matter will it be at 10°C?

Solid

Metal Characteristics

Solid at room temp (except mercury), lustrous, good conductors of heat and electricity, malleable

Specific Gravity Equation

Specific Gravity = Density of Substance/Density of H₂O at the same temperature (assumed to be 1.00 g/mL typcially)

How to write ionic coumpounds

Subscripts used to increase ion numbers so charge equal Subscripts must be reduced to lowest ration possible Cation always is first Ionic compound name is Cation element name (without ion) followed by anion name

Weighted Average Atomic Mass calculation

Sum of each isotope mass # * % Abundance

How to determine valence electrons

Sum of electrons in largest (number) shell

Dalton's Law

The total pressure exerted by a gas mixture of (Ptotal) is the sum of the partial pressures of the components in the mixture: Ptotal = Pgas1 + Pgas2 + Pgas3 +... Says that the percentage (moles A/total moles) of each gas in the mixture is equal to the pressure percentage that each gas contributes (Pa/Ptotal)

Stronger IMF between molecules mean more energy is required to change state. What does this mean for melting and boiling points?

They are higher

Sn⁴⁺ ion name

Tin (IV)

If you increase pressure, which way will the equilibrium shift?

To the side of the reaction with fewer moles of gas (to reduce squishing particles close together)

If you remove a substance, which way will equilibrium shift?

To the side where the substance was removed

Group B (periodic table)

Transition Metals (middle of table)

Which of the following is not an element 1. Carbon 2. Oxygen 3. Hydrogen 4. Water

Water

London Dispersion IMF

Weak (0.5-2.5kcal/mol, 2-10kJ/mol); occurs between all molecules, strength depends on size

Dipole-Dipole IMF

Weak (1kcal/mol, 4kJ/mol); occurs between polar molecules

Atomic mass

Weighted average of all isotopes

LeChatlier's Principle

When a stress is applied to a system at equilibrium, the equilibrium shifts to relieve the stress

Equilibrium

When the forward and reverse reaction rates become equal and the concentrations of reactants and products have reached constant levels (rate forwards = rate backwards)

Naming binary covalent compounds

Written with nonmetal further left is first, use prefix (if subscript is not one) to indicate number of atoms; The second element has ending -ide along with prefix --even if it is one

Any digit in coefficient of scientific notation Significant?

Yes

Are all changes of state temperature dependent?

Yes

If there are 45 people in a room and 5 people in the hallway which 3 people per minute moving from the room to the hallway and 3 people per minute moving from the hallway to the room, is this at equilibrium

Yes

Nonzero Digit Significant?

Yes

Zero at the end of a decimal number Significant?

Yes

Zero between nonzero digits Significant?

Yes

Can molecule with polar bonds be non-polar?

Yes - if molecule is symmetric

What must total charge equal in ionic compound?

Zero

Acid name if anion ends in -ite

________ous acid

Acid name if anion ends in -ate

_______ic acid

Melting ice has ∆H = +1.44 kcal and ∆S = +5.27 cal/k Which of the following are true? a. melting is endothermic b. melting is exothermic c. melting results in an increase in entropy d. melting results in a decrease in entropy e. melting happens spontaneously at all temperatures f. melting happens nonspontaneously at all temperatures g. melting happens spontaneously only at temperatures above 0°C h. melting happens spontaneously only at temperatures below 0°C

a, c, g (when ∆H is unfavorable but ∆S is, reaction only occurs spontaneously at "high" temperatures)

Compare the boiling points and structures of CO₂ and CH₂O. a. Which has a stronger IMF? b. How do these molecules differ from each other?

a. CH₂O because it has a higher boiling point b. CO₂ is nonpolar, CH₂O is polar

Reaction has ∆H = -17.4 kcal and ∆S = +27.2 cal/k a. Is this reaction exothermic or endothermic? b. Does entropy increase or decrease? c. At which temperatures is this reaction spontaneous?

a. Exothermic b. Increase c. All temperatures

In exothermic reactions... a. ∆H (enthalpy) <0, is this favorable or unfavorable for spontaneity? b. ∆S (entropy) <0, is this favorable or unfavorable for spontaneity? ...Why?

a. Favorable - release heat as molecules move slower b. Unfavorable - molecules become more orderly arranged

Compare HBr and HF a. Which will have larger LDF? b. Which has stronger IMF, based on boiling point?

a. HBr is bigger = stronger LDF b. HF has higher boiling point = stronger IMF

Fe³⁺ + SCN⁻ ↔FeSCN²⁺ a. If you have 2 moles Fe, 6 moles of SCN, and 3 moles of FeSCN, what is the equilibrium constant? Does it favor forward or reverse reaction? b. If you have 6 moles Fe, 7 moles SCN, and 3 moles FeSCN, what is Q? Do you need to change reactants into products or change products into reactants for equilibrium to be restored? c. How many moles of each will there be once equilibrium is restored? d. If reactants are removed an you have 2 Fe, 1 SCN, and 5 FeSCN, what is Q, and how do you restore equilibrium? e. What should the mixture be after you restore equilibrium? f. If you had an equilibrium mixture with 5Fe and 8SCN, how many FeSCN molecules should you have?

a. K(eq) = 0.25, favors reverse b. Q = 0.071, change reactants into products c. 4 moles Fe, 5 moles SCN, 5 moles FeSCN d. Q = 1.7, Change products into reactants e. 4 Fe, 3 SCN, 3 FeSCN f. 10

Melting ice has ∆H = +1.44 kcal and ∆S = +5.27 cal/k a. Will this reaction be spontaneous at -10.0°C? b. What would ∆H and ∆S be for the reverse reaction (freezing)? c. Will the reverse reaction be spontaneous at -10.0°C?

a. No b. ∆H = -1.44 kcal and ∆S = -5.27 cal/k c. Yes -- since melting is only spontaneous above 273K, the opposite reaction will only be spontaneous below 273K

CH₄(g) + H₂O(g) ↔ 3H₂ + CO(g) Determine if the "stress" will shift left (to reactants), right (to products), or have no effect a. CO removed b. H₂ added c. Pressure increased d. CH₄ added e. Heat added f. H₂O removed

a. Right shift b. Left shift c. Left shift d. Right shift e. Right shift f. Left shift

A reaction has ∆H = -844 kJ and ∆S = -1650 J/K a. Is it endothermic or exothermic? b. Does entropy increase or decrease? c. At what temperatures is this reaction spontaneous? d. Calculate ∆G at 275°C

a. exothermic b. decrease c. temperatures below 512K d. +60.2 kJ

What does it mean if... a. K is much small than 0.001 b. K is between 0.001 and 1 c. K is between 1 and 1,000 d. K is much larger than 1,000

a. only reactants are present at equilibrium; essentially no reaction occurs b. More reactants than products are present at equilibrium (reverse reaction favored) c. More products than reactants are present at equilibrium (forward reaction favored) d. Only products are present at equilibrium; reaction goes

a. Q=K b. Q<K c. Q>K

a. reaction is at equilibrium b. reaction is going backwards more than forwards and must shift forward to restore equilibrium c. reaction is going forwards more than backwards and must shift backward to restore equilibrium

In endothermic reactions... a. ∆H (enthalpy) > 0, is this favorable or unfavorable for spontaneity? b. ∆S (entropy) > 0, is this favorable or unfavorable for spontaneity? ...Why

a. unfavorable - they require heat input as molecules move faster b. favorable - they become more random as molecules become more spread out

Factors that affect reaction rate

activation energy (energy needed to start reaction - can be lowered by a catalyst), concentration of reactants, and temperature (affects speed of particles)

Specific heat

amount of energy required to change the temperature of 1 g of a substance by 1°C

actual yield

amount of product actually obtained in reaction

theoretical yield

amount of product that can be made before limiting reagent runs out

Polar Covalent bond

atoms have EN difference of 0.5-2, electrons shared unequally, more EN atom hogs electrons

Nonpolar Covalent bond

atoms sharing elections with EN difference of <0.5, electrons shared equally

How to calculate excess reagent

calculate amount of it needed to make the theoretical yield of product; then subtract the amount used from starting quantity

Equation for the temperature at which a reaction changes spontaneity

can be calculated at the T vale for which ∆G = 0 so T=∆H-∆S

Ionic bonds are between

cation and anion

Formal Charge

charge any atom would have if the bonding electrons were shared exactly equally, MUST add up to equal molecule's charge

10 prefix

deca-

-∆S

decrease in disorder

2 prefix

di-

Ionic bond

electrons not shared at all (EN difference >2

reverse of exothermic reaction

endothermic

Enthalpy and spontaneity

endothermic (+∆H) is unfavorable for spontaneity exothermic (-∆H) is favorable for spontaneity

What results in positive q and positive ∆T

energy addition

Electron affinity definition and trend

energy released on dding an electron to single atom in gaseous state, the ease with which an atom gains an electron, Gets larger to right of periodic table

What results in negative q and negative ∆T

energy removal

Heat of Vaporization/Fusion

energy required to break intermolecular forces

What do ∆H values indicate

enthalpy of reaction; energy associated with a reaction

Net ionic equation

equation that has the spectator ions removed

reverse of an endothermic reaction

exothermic

What does subscript tell me about moles and atoms?

for every one mole of a compound, the subscript indicates the number of moles of an element; and for every one molecule of a compound, the subscript indicates how many atoms of an element there are

Reduction

gain of one or more electrons by an atom

Endothermic Reaction

heat is absorbed (energy is positive) or ∆H is positive; heat is a reactant

Exothermic Reaction

heat is released (energy is negative) or ∆H is negative; heat is a product

7 prefix

hepta-

6 prefix

hexa-

What do coefficients indicate?

how many moles of reactants react and how many moles of product are formed used to convert from moles to moles of two substances

Acid name if anion ends in -ide

hydro_______ic acid

+∆S

increase in disorder

Precipitate

insoluble solid product

Spectator Ions

ions that are unchanged on both sides of the reaction arrow

Oxidation

loss of one or more electrons by an atom

Molar mass

mass of one mole of substance in grams used to change between moles and grams calculated by adding masses of atoms in chemical formula from periodic table SHOULD BE ROUNDED TO ONE DECIMAL PLACE

Entropy

measure of the amount of disorder in a system; measured in cal/(mol*K) OR J/(mol*K)

Entropy Change ∆S

measure of the increase or decrease of disorder as a chemical reaction or physical change occurs: affected by many things such as temperature, state of matter, and number of particles present

Electronegativity (EN)

measures how much an atom can attract electrons

Free-energy change (∆G)

measures the change in free energy as a chemical reaction or physical change occurs (takes into account ∆H and ∆S and temperature)

Give molar mass, number of moles, number of atoms of oxygen, a number of molecules for 48g of sulfur trioxide

molar mass = 80.1 g/mol moles = .60 mol atoms of oxygen = 1.1x10²⁴ molecules = 3.6x10²³

1 prefix

mono-

+∆G

non-spontaneous (endergonic)

9 prefix

nona-

Avagadro's number

number of particles of substance in one mole quantity 6.022x10²³ Used to change between moles to atoms or molecules One mole of element has 6.022x10²³ atoms One mole of compound has 6.022x10²³ molecules

8 prefix

octa-

How to draw electron dot symbols

one dot=one valence electron and each side gets an electron before any side gets two

Anions (negative) form when

one or more electrons are gained

Cations (positive) form when

one or more electrons are lost

Precipitation reactions

one product is insoluble, forming a solid (soluble product dissociates into spectator ions)

Ionic compound formed from

oppositely charged ions

5 prefix

penta-

Percent yield equation

percent yield = actual yield/theoretical yield times 100

Nonmetal Characteristics

poor conductors of heat and electricity, eleven are gases at room temp, six are brittle solids, one is liquid

Partial pressure

pressure exerted by each gas in a mixture and is the same pressure that the gas would exert if it were alone

Reducing agent

reactant that contains the oxidized element

Oxidizing agent

reactant that contains the reduced element

Limiting reagant

reactant that runs out first and limits amount of product made

What qualifies as a substance in an equilibrium equation?

reactant, product, or heat

Neutralization reactions

reactants are an acid (H+ cation) and a base (OH-) anion; products are water and an ionic compound (salt) formed from base cation and acid anion when cations switch places (double replacement)

excess reagent(s)

reactants left over after the theoretical yield is reached

Oxidation-Reduction (Redox) Reactions

reactions in which electrons are transferred

Q = reaction quotient How to calculate

same way as K; it will tell you where the reaction is at with respect to equilibrium

Reaction rate

speed at which a chemical reaction takes place; depends on number and force of collisions between molecules and molecule orientation upon collision

-∆G

spontaneous (exergonic)

Resonance Structures

structures that differ in the placement of multiple bonds, but not in the arrangement of atoms, denoted with a ↔

4 prefix

tetra-

Which ion are acids named from?

the anion

Ionization Energy definition and trend

the ease with which an atom loses an electron to form cation/ energy required to remove valence electron from single atom in gaseous state, Gets larger to right of periodic table

Given ∆H values are per coefficient mole of each reactant and product; What can this determine?

the heat absorbed or released for the reaction of a specific amount of reactant or product

Vapor Pressure

the partial pressure of vapor molecules in equilibrium with a liquid; increases with temperature. once vapor pressure = atmospheric pressure, boiling occurs

What does electron configuration list?

the subshells and how many electrons are in each one

In changes of state, what do molecules do?

they get farther apart or closer together

3 prefix

tri-

Double Replacement Reactions

two ionic reactants, cations trade places for two new ionic products

Calculate formal charge

valence electrons - (1/2 the shared electrons + all lone electrons)--- do this for each atom in the molecule to determine which resonance structure is best

∆G equation

∆G = ∆H - T∆S

∆H Equation

∆H = [∑(Bond Dissociation Energies)reactants - ∑(Bond Dissociation Energies)products]