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Compare the bond enthalpies of the carbon-carbon single and triple bonds. Based on this information, what is the average π-bond contribution to bond enthalpy in C≡C? C-C: 348 kJ/mol C=C: 614 kJ/mol; C(triple)C:839 kJ/mol
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what is the average π-bond contribution to bond enthalpy in N≡N?
N-N: 163 kJ/mol; N=N:418 kJ/mol; N(triple)N: 941 kJ/mol
N-N: 163 kJ/mol; N=N:418 kJ/mol; N(triple)N: 941 kJ/mol
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chem exam 3
| Question | Answer |
|---|---|
| Compare the bond enthalpies of the carbon-carbon single and triple bonds. Based on this information, what is the average π-bond contribution to bond enthalpy in C≡C? C-C: 348 kJ/mol C=C: 614 kJ/mol; C(triple)C:839 kJ/mol | 246 kJ/mol |
| what is the average π-bond contribution to bond enthalpy in N≡N? N-N: 163 kJ/mol; N=N:418 kJ/mol; N(triple)N: 941 kJ/mol | 389 kJ/mol |
| Draw the Lewis structures of C2H6, C2H4, and C2H2. | part C # 1 chp 7 |
| Draw the Lewis structures of N2H4, N2H2, and N2. | part D #1 chp 7 |
| In the three types of nitrogen-nitrogen bonds, each N atom has a ___ _______of electrons. | lone pair |
| In the three types of carbon-carbon bonds, no ________ repulsions exist, and so the σ and π bonds have more similar energies. | lone-pair |
| In nitrogen-nitrogen bonds, repulsions between bonds and the lone pair of electrons is minimized going from approximately 109.5-degree to 120-degree to 180-degree bond angles, making the π bonds_______ relative to the σ bond. | stronger |
| The Lewis structure for a molecule allows you to predict its shape, bond angles, and hybridization based on the number of ____ _______ on the central atom. | charge clouds |
| 2 clouds; what is the shape, angle, and hybrid orbitals? | linear, 180, sp |
| 3 clouds;what is the shape, angle, and hybrid orbitals? | trigonal planar, bent; 120; sp^2 |
| 4 clouds; what is the shape, angle, and hybrid orbitals? | tetrahedral, trigonal pyramidal, bent; 109.5; sp^3 |
| 5 clouds; what is the shape, angle, and hybrid orbitals? | sp^3d; trigonal bipyramidal, seesaw, T-shaped; 90, 120, 180 |
| 6 clouds ; what is the shape, angle, and hybrid orbitals? | octahedral, square pyramidal, square planar; 90, 180; sp^3d^2` |
| Draw the electron-dot structure for CHClO. | part A # 2 chp 7 |
| What the molecular shape (geometry) of CHClO? | trigonal planar |
| What are the approximate bond angles in CHClO? | 120 |
| What type of hybridization is exhibited by the central atom in CHClO? | sp^2 |
| learning goal #3 chp 7 | |
| How many valence electrons are in an atom of sulfur? | 6 |
| The orbitals with the same energy are known as________ orbitals. | degenerate |
| In the molecule SF4, sulfur makes four covalent bonds. Therefore, four of its six valence electrons need to be unpaired. How many degenerate orbitals are needed to contain six electrons with four of them unpaired? | 5 |
| What is the name of the hybrid orbitals used by sulfur in SF4? | sp^3d |
| The number of electron domains around a central atom includes all ______ and ________ electron pairs. It can be used as an indicator of the hybridization of the central atom as shown in the table. | bonding and nonbonding |
| What is the hybridization of the central atom of each of the following molecules? BF3, SiCl4, PF5 | BF3= sp^2 SiCl4 = sp^3 PF5 = sp^3 d |
| Hybridization is used to explain not only the number of bonds formed in a compound but the_________ of these bonds. | equivalence |
| Sulfur forms the following compounds with chlorine. Identify the type of hybridization for the central sulfur atom in each compound. SCl2, SCl4, SCl6 | SCl2 = sp^3 SCl4= sp^3d SCl6 = sp^3d2 |
| part B # 5 chp 6 | |
| Draw the Lewis structure for the CCl4. Select the correct hybridization for the central atom based on the electron geometry CCl4. | chp 7 #6 part A; sp^3 |
| Draw the Lewis structure for the NH3. Select the correct hybridization for the central atom based on the electron geometry NH3. | chp 7 #6; sp^3 |
| `Draw the Lewis structure for the OF2. Select the correct hybridization for the central atom based on the electron geometry OF2. | chp 7 #6; sp^3 |
| Draw the Lewis structure for the CO2. Select the correct hybridization for the central atom based on the electron geometry CO2. | cp 7 #6; sp |
| chp 7 #7 | |
| The molecule 2-butene, C4H8, can undergo a geometric change called cis-trans isomerization. transformations can be induced by light and are the key to human visionRotation about the ______ bond, which breaks the π bond, is required for the isomerization. | C=C |
| #9 chp 7 | |
| The average bond enthalpy for a C=C double bond is 614 kJ/mol and that of a C−C single bond is 348 kJ/mol. Estimate the energy needed to break only the π bond of the double bond of 2-butene. | 4.42 x 10^-19 J/molecule |
| What is the longest wavelength λ of light that will provide photons of sufficient energy to break the π bond and cause the isomerization? 4.42 x 10^-19 J/molecule | 450 nm |
| # 10 chp 7 | |
| A_________ reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. An example of a chemical reaction is the formation of water from hydrogen and oxygen gas. | chemical |
| In a_______ change, a substance changes its physical appearance but not its chemical identity. An example of physical change is the formation of liquid water from solid water, a familiar process called melting. | physical |
| ?H3PO4+?Mg(OH)2→ ?Mg3(PO4)2+?H2O | 2, 3, 1, 6 |
| balance K2SO3(aq)+MnCl2(aq)→ MnSO3(s)+KCl(aq) | 1,1,1,2 |
| balance NH4NO3(aq)→ N2O(g)+H2O(l) | 1,1,2 |
| balance Cl2(g)+NaOH(aq)→ NaCl(aq)+NaClO3(aq)+H2O(l) | 3, 6, 5, 1, 3 |
| balance Al(s)+FeSO4(aq)→ Al2(SO4)3(aq)+Fe(s) | 2,3,1,3 |
| 3H2(g)+N2(g)→2NH3(g) How many moles of NH3 can be produced from 19.5 mol of H2 and excess N2? How many molecules (not moles) of NH3 are produced from 5.08×10−4 g of H2? How many grams of NH3 can be produced from 2.34 mol of N2 and excess H2. | 13, 79.7, 1.01*10^20` |
| balance CH4(g)+O2(g)→ CO2(g)+H2O(g) What mass of carbon dioxide is produced from the complete combustion of 4.20×10−3 g of methane? What mass of water is produced from the complete combustion of 4.20×10−3 g of methane? What mass of oxygen needed? | 1,2,1,2 1.16*10^-2 g 9.45 x 10^-3 g 1.68 x 10^-2 g |
| 12.00 g of CaCO3 powder and add it to 48.60 g of HCl solution. You then weigh the resulting solution and find that it has a mass of 55.68 g . what mass of CO2 was produced in this reaction? CaCO3(s)+2HCl(aq)→H2O(l)+CO2(g)+CaCl2(aq) | 4.92 g |
| # 8 chp 8 | |
| ?C6H14(g)+?O2(g)→ ?CO2(g)+?H2O(g) BALANCE Determine how many moles of O2 are required to react completely with 5.7 moles C6H14. | 2, 19, 12, 14 54 mol |
| 2Al(s)+3Cl2(g)→ 2AlCl3(s) You are given 27.0 g of aluminum and 32.0 g of chlorine gas. If you had excess chlorine, how many moles of of aluminum chloride could be produced from 27.0 g of aluminum? | 1.00 mol |
| 2Al(s)+3Cl2(g)→2AlCl3(s) You are given 27.0 g of aluminum and 32.0 g of chlorine gas. If you had excess aluminum, how many moles of aluminum chloride could be produced from 32.0 g of chlorine gas, Cl2? | .301 mol |
| 2Al(s)+3Cl2(g)→2AlCl3(s) You are given 27.0 g of aluminum and 32.0 g of chlorine gas. What is the maximum mass of aluminum chloride that can be formed when reacting 27.0 g of aluminum with 32.0 g of chlorine? | 40.1 g |
| balance C8H18(g)+O2(g)→CO2(g)+H2O(g) | 2, 25,16, 18 |
| 2C8H18(g)+25O2(g)→16CO2(g)+18H2O(g) 0.310 mol of octane is allowed to react with 0.650 mol of oxygen. Which is the limiting reactant? | oxygen |
| 2C8H18(g)+25O2(g)→ 16CO2(g)+18H2O(g) How many moles of water are produced in this reaction? After the reaction, how much octane is left? | .468 mol .258 mol |
| 2Al(s)+3H2SO4(aq)→ Al2(SO4)3(aq)+3H2(g) Suppose you wanted to dissolve an aluminum block with a mass of 15.3 g . What minimum mass of H2SO4 would you need? What mass of H2 gas would be produced by the complete reaction of the aluminum block? | 83.4 g 1.71 g |
| 3H2(g)+N2(g)→ 2NH3(g) 1.80 g H2 is allowed to react with 10.1 g N2, producing 2.69 g NH3. What is the theoretical yield in grams for this reaction under the given conditions? What is the percent yield for this reaction under the given conditions? | 10.1 g ; 26.5% |
| 2Mg(s)+O2(g)→2MgO(s); When 10.1 g Mg is allowed to react with 10.4 g O2, 12.1 g MgO is collected. Determine the limiting reactant for the reaction. Determine the theoretical yield for the reaction. Determine the percent yield for the reaction. | magnesium; 16.8 g; 72.0% |
| #15 ch. 8 | |
| electronegativity trend is _____ and ______ on periodic table | up and right |
| _______ covalent= unequal sharing ________ covalent = equal sharing | polar; nonpolar |
| _______ dissolves polar, ________ dissolves nonpolar | polar; nonpolar |
| Which bond is more polar? B-Cl or C-Cl which bond is more polar? P-F or P-Cl | B-Cl P-F |
| formal charges = ? | # of valence - (unshared (LP) + 1/2(shared(bonds))) |
| exceptions the the octet rule: 1) _____ number of electrons 2)____ than an octet 3) ______ than an octet | odd; less; more |
| Aluminum is happy with ____ electrons when with chlorine | 3 |
| group _______ tends to be less than an octet | 13 |
| n> ____ tends to be more than an octet (P, S, As, I) | 3 |
| VSEPR | valence shell electron pair repulsion |
| in a seesaw molecular geometry, where does the lone pair go? | the very left most |
| in AB5E, does it matter where the one pairs go? | no |
| in AB4E2, where do the lone pairs go | across from each other in the plain |
| in diatomic atoms, the bond dipole = ________ | polarity |
| in polyatomic atoms, need more bond dipoles, so polarity = ____ ___ ______ | net dipole moment |
| how do you know something will be nonpolar | it is one of the 5 basic structures with same surrounding structures and no lone pairs |
| ______ of vector and its ________ tells how polar | length and direction |
| corrosive ness - chemical or phsyical | chemical |
| density - chemical or phsyical | physical |
| color - chemical or phsyical | physical |
| flammabiltiy - chemical or phsyical | chemical |
| odor - chemical or phsyical | physical |
| acidity - chemical or phsyical | chemical |
| what is general pattern we will use in stoichometry | g - moles - moles - g |
| ______ yield - maximum amount theoretically made | theoritical |
| 2m(alkali metal) + x(halogen)2 --> | 2mx |
| 2 m (alkali metal) + 2H20 --> | 2m + + 20H - + H2 |
| homogenous mixture of 2 or more substances | solution - can't see phase boundaries |
| substance in greater quantity = | solvent |
| subtance in lesser quantity = | solute |
| amount of solute in amount of solvent | concnetration |
| amount of solute / amount of solvent is measured in | mol/L, mol/kg |
| molarity = | moles of solute/ volume of solution (moles/L) M |
| dissolve to produce H+ ions, pH<7, sour, litmus red | acids |
| dissolve to produce OH- ions, pH>7, bitter, litmus blue | bases |
| a ______ acid dissasociates completely; a ______ acid does not | strong; weak |
| what are the strong acids? | HCl, HBr, HI, H2SO4, HNO3 |
| strong bases? | alkali metals with hydroxide |
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