Test 3 Key

Test 3 Key - CHM1045 Test 3 (Fall, 2006) version A...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CHM1045 Test 3 (Fall, 2006) version A Instructor: Prof. Bush Name Recitation Number (Show all your work. No books or notes are to be used during this test. There are nine problems on 3 pages plus a periodic table at the end. Please verify that you have all pages) 1. a, If 7.94 mL ofa stock solution oi‘BaCl; were required to be diluted in order to prepare 196 mL of a/QJAM solutionj what was the concentration of the initial stock solution? ' , ‘ "~~\\ 3 / M l V l ‘\.\‘~ [\ Ml:M2V2/(Vl):(0.24M x 1961nL)/7.94mL = 5.92M \ \ \._ b. What volume in milliliters of2.29 M (NH4)1804 should be used to prepare 0.1 15L ofa 0.32 M solution‘i/k .,—_ 4/’ i' ‘\ \ *Viémzvz/Mi : (0.32 M x 1 15mL)/2.29M : 16.] tfitx \ , ._‘_»___>_ng___ ,__>_ ‘ V 7 fl 7 _ r r 3 2. In order to determine the molar mass of an unknown strong acid. a chemist performs a titration with sodium hydroxide. Calculate the molar mass of this acid. HZA. assuming 5.19g of the acid reacts with 23.45 mL of0.452M NaOH. Assume that the unknown acid is diprotic. 100% pure. and dissolves. dissociates and reacts completely according to the following reaction: HzA + on' —> A2' + 21120 0 023451. x 0.452Mol/L : 0.l06 mol NaOH x lmol HzA/Zmol OH- 2 0.053 / \ MW : g/mol = 5.19g HZA / 0.053 mol : 979g/mol 3. Jet‘fis a Very clumsy chemist; when he attempts to measure the pH of rainwater. which normally has a hydrogen ion concentration of2.5 x 10'6 M. he inadvertently spills it all over his lab bench which had previously been exposed to acid. After he transfers the remaining rain water from the bench top into a beaker to measure the pll. he finds it to be at pH : 4.25. Please save Jeff from getting tired! Calculate the pH of the original rain water from the reported hydrogen ion concentration and then to see how badly he screwed up. calculate the hydrogen ion concentration of the rainwater after he spilled it (at pll=4.25) / “1'0, 100(—pH):[H+]:10004.25): Aft Z '9 c_// L' A m f/ PH=-10ng+]=—log(2.5x10’6): /~, if: (Tu/€54,431ch {\C‘ctn L7 ,. v" i \ 4. Using Hess's Law and the following reactions and thermodynamic data: 3 C(s) + 4 Hz(g) —) C3Hg(g) L‘sH‘VkJ = 403.8 ngmft’ug its“. < "I C(s) + 02(g) ~+ C02(g) AH‘VkJ = -393.5 “Lax?” { ,v a 2’5 0 v _ / v 1 L - f; \(y/ (3/ H2(g) + 1/2 02(g) «i H20(g) AH /li — -241.8 ' y [I ,‘. Calculate the enthalpy, AHM of the following reaction: \lZLE «2116"? kiwi/pg) C3H8(g) + 5 02(g) ")3 C02(g) + 4 H20(g) V/ ‘ _ -\ x . 5 en '2‘} - i A “ Z L j l“ m (PC; g/Q—‘wglfigi (j $ A H 2 34 Hi: - Hat.) :2 K1 "i" 5/" ’r/f/ '\ ’36:; A - - 2% r 5 {2,2 we “r (-150 AH : Urea : 4w, m .n i I . . “l 4 f“ . . A 3 . 1 W2. + ‘l/z : lO/L o; «: 50L Army, '2 4% +341 5. From the standard enthalpy change for the following reaction and from the given standard a enthalpies of formation. calculate the standard enthalpy of formation of methane (CH4) 3) (J‘ l‘] 4}! CH4(g) + 2 02(g) *‘)C03(g) + 2 H200) Aurxn" = -890.4 M , d t _ . .x. .— .‘s w 7 l : AH°-CO (g)=-393.5 kJ/mole 4 a “ 4 / , ,_ 3‘2: COL/3,7 ; AH“: 3126(1): -285.9 kJ/mole l ll "XII ‘ Z f’Fé‘cl [fir/wrath K] / \ 5 ‘ ~= fell}, 4* ,t- ‘ml‘filli , » 285,7kJ ‘V ,\ , ‘I‘in lllclg '4‘ “F /M() +(fi373'5k—J) , I I5 £291 {shaggy ‘1 . .t;;(' i ' A i- i~ \ ls ~ , thec t‘ _ a, .,, I 7 l A¥r§(tr\ fly J um , ( //::’i’~ i“, V _, . (My): — 7o};- 10 its)? 6. In a coffee cup calorimeter, 25.0m14 ofO.lOOl\7hAgNO3 and 25.0 erofO. 100 M K1 are mixed. If the two solutions were initially at 22.600C and after reaction. the final temperature was 23.94"(‘. calculate AH“ (kl) for the following reaction. Assume the specific heat capacity ofthe solution is the same as that for pure water, 4.184 .lg’lK". Assume that no heat is lost to the surroundings. (The molecular weights of silver nitrate and potassium iodide are l70g/mol and 166g/mol. respectively) (Hint 7 find the total mass of reacting species first) ( [ngmw‘l‘ Fflfiéufil y Ag+(aq)+1'(aq) ~>Ag1(s) AR 2 p. a: I W a I Csz X C I ll'lCAI: m\\ LP [J‘l n m_ C . a 1* . - “\z ( . " ' T Ms K '7‘ W : 0'”?ilj‘r"k\al:wvet 0 02“ 7 _ lWI' AER/703 _ i ‘3' r- [ 7LI’C Q: lVlM’é [58 [<" R ‘ll‘la7leO T A 77?? :mtsaif . LVN” lm‘ KI: TI?)th WES: 7. The change in internal energy ofa gas mixture in a bomb calorimeter is known to be -l725 kJ when a certain stoichiom ' ‘ 'xture of hydrogen gas and oxygen gas are combusted. What Cm/punt of work is don by the gas n the surroundings, if 12] 7k] 01‘ heat is simultaneously losflo the surroundings. LE: clerk» l/U : Alsz W“; N: ~1725KT~1217KS): ~ 505 Ky 8. What amount of heat energy (H) is released in the combustion of 10.0 g of (73148? C3Hg(g) + 5 02(g) "-9 3 CO1(g)+ 4 H200) AH" = -2221.6 kJ/mol [@jg/Cjiilé X H2221,(ka 4 ’7 r . a ,Efii'lb 1"“ 'l'ls " “90m 9. Often it is desirable to produce Visible light with the neodymiumzYAG laser. This can be done by sending an infrared light pulse through a special crystal. The crystal can combine a pair of infrared photons into a single green photon emitted at 532 nm. Calculate the energy of one quantum of green photons at this wavelength if the speed of light is 3.0 x 1 OR m/s and Planck‘s constant is 6.63 x 10"“Js‘.’ What is the frequency 01‘ these same photons? ...
View Full Document

This test prep was uploaded on 04/17/2008 for the course CHM 1045 taught by Professor Bush during the Spring '08 term at FSU.

Page1 / 3

Test 3 Key - CHM1045 Test 3 (Fall, 2006) version A...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online