DO NOT WR ITE ON THIs EXAM MULTIPLE CHOICE. Choose the one alternative that best
ID: 590967 • Letter: D
Question
DO NOT WR ITE ON THIs EXAM MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Read the volume of liquid pictured in 10 the buret at the right. Report the buret reading to the correct number of significant figures. B)10.15mL c)RaLD) 10.25 E)10.3 mL 4)10.200 rL 2) Calculate the change in enthalpy, aH for the following reaction NaOH(aq) + Ha(aq) NaCl(aq) + H2O(R) given the data NaOH(s) NaOH(aq); H--468 kJ A)+502 k B)-50.2k c)-468 k D) +468 k E)-147.2k 3) A 5.00 gram sample of compound X was dissolved in 25.00 g of DI H20 in an 8 oz styrofoam cup. The emperaturerose from 19.8 oC to 25.00C. If the specific heat of the solution is approximately equal to the spedific heat of water, 4.184J/(goC) and the formula weight FW of X is 95.8what is theaH for the reaction A) -65X 102 /mol B)125x 104 J/mol C)-1.25 X 104 1/mol D) 4.35 X 104J/mol E)65x 102 /mol 4) Which molecular equation best represents the reaction that occurs when an aqueous solution of lead nitrate Pbi(NOs)2 is mixed with an aqueous solution of potassium iodide, KI? A) Pt,2+(aq) + 2N03-(aq) + 2K+(aq) + 21-(aq) Pt12(s) + 2K+(aq)+2N03-(aq) C) No Reaction Oocurs D)K"(aq) + NO3" (aq) KNO3(s) 1-1Explanation / Answer
1) Consider the reading at lower meniscus of the liquid which is 10.7mL, Option C)
2) NaOH (aq) -----> NaOH (s) H = + 46.8 kJ/mol
NaOH (s) + HCl (aq) ---------> NaCl (aq) + H2O (l) H = -97 kJ
Add these 2 equations to get,
NaOH (aq) + HCl (aq) ---------> NaCl (aq) + H2O(l) ; H = +46.8 -97 = -50.2 kJ
Option B is the answer.
3) Mole of X produced = 5gm / 95.8 gm/mol = 0.05219 mol
Q = (25+5) gm * 4.184 J/ gmoC * (25-19.8)oC = -652.704 J
H = - (652.704)J / 0.05219 mol = -1.25*104 J/mol, Option C is the answer.
4) Pb+2 (aq) + 2I- (aq) -------> PbI2 (s) yellow precipitate , option B is the answer
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