Foothill College Nov. 18, 2009 Chem25 Exam2B Constants/Conversions

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1 Constants/Conversions atm = 0.35 J J = 0 7 erg R H =.8 x 0-8 J ev = kj/mol atm = 760 torr = 760 mm-hg =.035 x0 5 Pa C=3.00 x 0 8 m/s e =.60 x 0-9 Coul amu= x 0-4 g N A = 6.04 x 0 3 h = 6.66 x 0-34 JS R = J/K mol = L atm/ K mol k = x 0 3 J/K Cal = 4.84 J L Equations E = hv C= vλ E = hc/λ π = MRT λ = h/mv K = C EΨ = HΨ ΔE = q + w E cell = E red + E ox ΔT = k f m ΔT= k b m q = CΔT = n CΔT = m s ΔT q P ΔH Vap E n = (-R H ) Specific Heat = ln ( ) = - n m ΔT P R T R /R = (M /M ) -/ E (Q + Q)/d nλ = d sinθ ΔG = ΔH -TΔS Ln A = ln A 0 -kt t / = 0.693/k k = A exp(-e a /RT) K P = K C (RT) Δn K a K b = K w = x 0-4 /A = /A 0 -kt F = 96,485 Coul/mol Cu + + e - Cu (S) E = [base].303 RT ph = pk a + log( ) ΔG = ΔG =RT ln (Q) E = E - log (Q) [acid] nf ΔS rxn = ΣnΔS f (products) - ΣmΔS f (reactants) ΔG = -nfe ΔH rxn = ΣnΔH f (product)-σnδh (reactant) P = χ P Total A 8A H He.008 A 3A 4A 5A 6A 7A Li Be B C N O F Ne Na Mg Al Si P S Cl Ar B 4B 5B 6B 7B 8B B B K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe (98) Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn (09) (0) () Fr Ra Ac Rf Ha Sg Ns Hs Mt (3) (6) (7) (6) (6) (66) (6) (65) (66) Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu (45) Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lw 3.0 (3) 38.0 (44) (4) (43) (47) (47) (5) (5) (57) (58) (59) (60) T

2 molecule ΔH f CH 4 (g) HCl(g) -9.3 CHCl 3 (l) -3.8 HF(g) CH 3 OH(l) CO(g) -0.5 HNO 3 (l) -73. CO (g) H O(g) -4.8 H O(l) -85.8

3 MULTIPLE CHOICE QUESTIONS (60) 0. Your Section number is A. 0 (Monday Lab) B. 0 (Wednesday Lab). Given that 4 NH O? NO + 6 H O, when 4.50 mol of H O are formed, the amount of NO formed is A..50 mol B mol C mol D mol. What is the gas produced when hydrochloric acid is reacted with ammonium carbonate? A. ammonia B. carbon dioxide C. chlorine D. hydrogen 3. Considering the following reaction: Pb(NO ) ( aq) KI( aq) PbI ( s) KNO ( aq) would be spectator ions? A. Pb +, NO 3 - B. Pb +, K + C. K +, NO 3 - D. K +, I Which ion(s) Which statement about boiling point is FALSE? A. The boiling point is higher for compounds with strong intermolecular forces. B. The boiling point of a compound is an absolute constant. C. The boiling point of a compound is higher for nonvolatile compounds. D. The boiling point is higher for compounds with a high viscosity. 5. Increasing the intermolecular forces of a liquid will do which of the following? A. decrease the evaporation rate B. increase the viscosity C. decrease the vapor pressure D. all of the above 6. What happens as you start to add heat to a solid substance? A. Thermal energy causes the components of the solid to vibrate faster in their stationary position. B. Heating of the now formed liquid results in increasing the liquid temperature. C. When the melting point is reached, the thermal energy is sufficient to overcome intermolecular forces holding the components stationary. D. all of the above 7. Which statement is true in describing what occurs when a solid melts to a liquid? A. The process is endothermic and the heat of fusion is negative. B. The process is exothermic and the heat of fusion is positive. C. The process is endothermic and the heat of fusion is positive. D. The process is exothermic and the heat of fusion is negative. 3

4 8. The rate of vaporization of a liquid can be increased by. increasing the surface area. decreasing the strength of the intermolecular forces 3. increasing the temperature A. only B. only C. 3 only D. and only 9. What is the limiting reactant for the following reaction given we have.6 moles of HCl and.4 moles of Ca(OH)? HCl + Ca(OH) HO + CaCl A. Ca(OH) B. H O C. HCl D. CaCl 0. A sample of 8.5 g NH 3 on oxidation produces 4.5 g of NO. Calculate the percent yield. 4 NH O? NO + 6 H O A. 5 % B. 60% C. 30% D. 70%. What type of a reaction occurs when a potassium nitrate solution is mixed with a barium acetate solution? A. precipitation B. acid-base neutralization C. gas evolution D. no reaction. A precipitate is expected to be formed when an aqueous solution of sodium sulfate is added to an aqueous solution of A. barium chloride B. iron(iii) chloride C. potassium chloride D. magnesium chloride 3. When elements combine to form compounds, A. their properties are an average of all elements in the compound. B. their properties change completely. C. their properties do not change. D. their properties are completely random. 4. Which noble gas has the highest boiling point? A. Ne B. Xe C. Kr D. Ar 4

5 5. Substance A is a molecular compound that dissolves in gasoline but not in water. The molecules of A are very likely: A. metallic. B. polar. C. nonmetallic. D. nonpolar. 6. The primary cause of increasing greenhouse gases is: A. the burning of vast amounts of rain forests. B. the production of CO by respiration. C. the increased use of natural gas, petroleum and coal. D. the release of CO by decreasing solubility in the ocean. 7. How many grams of water are made from the reaction of 4.0 grams of hydrogen gas? Given the reaction: H + O HO A. 8 B. 36 C. 7 D Which of the following compounds have the smallest formula mass? A. CO B. H O C. NO D. SiO 9. You have 0.0 g each of Na, C, Pb, Cu and Ne. Which contains the largest number of moles? A. Na B. C C. Pb D. Ne 0. Which of the following molecules contain A g H B g H O C. 8.0 g N D. 3.0 g O atoms? SHORT ANSWER (0 pts). Definition. (5 pts) A. Normal melting point B. Dipole-dipole forces C. Combination (synthesis) reactions D. Miscibility E. Molecular formula. Nomenclatures A. Aluminum carbonate B. Aluminum sulfite C. Cu 3 (PO 3 ) D. SO 3 E. HIO 5

6 3. How many joules of heat are needed to completely vaporize 4.40grams of water at its boiling point? ( Δ H = 40.6 kj/mol ) vap [(4.4 g)/(8.0 g/mol)] x (40.6 kj/mol) = kj 4. Evidences of a chemical reaction occur. LONG ANSWER (0 pts each). What is the limiting reactant, theoretical yield, and percent yield for the following reaction given we have g of Ca(NO 3 ), of Li 3 PO 4 and 53.7 g of calcium phosphate produced? (you must write a balanced chemical equation) 3Ca(NO3) + Li3PO4 6LiNO3 + Ca3(PO4).5 pts MM mass mole pts pts mole/coef pts pts pts LR pt pts pt.5 pts TY AY= 53.7 PY= (AY/TY)x00% = A compound contains 3.58 g of carbon,.76 g of hydrogen and 3.45 g of oxygen. It has a molar mass of 80.5 g/mol. What is its molecular formula? Mass mole mole ratio n E. F. M. F. C H O Molar mass pt pt pts pt Formula weight pt n = pt 6