Chemistry Questions and Answers April 14, 2020

For the reaction if percentage dissociations of N,04 are 20, 45 ,65 ,80 Then the sequence of observed vapour densities (at equilibrium) will be (A) dz0 d45 dgs dso (B) dgo d65 d45 d20 08p 9p Sp 07p ()) (D) (d20 d4s) (de5 dg0)

You have isolated a new enzyme. It cleaves a 5 residues peptide to a 4 residues peptide. It is inhibited by chelating agents, chemicals that tightly bind metals. It loses activity if the pH drops below 5. The catalytic parameters for different peptides are shown below. peptide Kcat, min 1 Km mM AAEY 100 15 AAQY 40 2 AARY 300 23 AAQF 100 4 Which is

Create a table of expected H NMR signals Crossed Aldol Aldol Elimination Recrystallized Product (prediction) Product (prediction) Product OH H. Total Integration of All Protons Total Integration of Alkyl Protons 8 Total Integration for all CH2 Protons Splitting pattern for CH2

Provide IUPAC names of the following two compounds. a) H3C H. OH b) H3C CH3

4. (20pts) Consider a mixture of 50.0 mL of 0.100 M HCi and 50.0 mL of 0.100 M acetic acid. Acetic acid has a K, of 1.8 x 105. a. Calculate the pH of both solutions before mixing. b. Construct an ICE table representative of this mixture. c. Determine the approximate pH of the solution. d. Determine the percent ionization of the acetic acid in this

6. A fluoride ISE immersed in 1 x 102 mol dm 3 solution of sodium fluoride gives a potential of 35,2 mV and when it is immersed in a tooth paste solution it gives a potential of 30,2 mV. What is the concentration of fluoride ion in the toothpaste (En E) pF mk pFa unk std unk 0.0591

Predict the neutral organic product of the reaction. Select Draw Rings More H. H2SO4 HO

A solvent passes through a chromatography column in 3.09 min, but the solute requires 9.80 min. The volume of the stationary phase is 0.165 times the volume of the mobile phase in the column (Vs 0.165VM). What is the distribution constant, Kp, for this system Kp 12.12 Incorrect An open tubular chromatography column is 30.2 m long with an inner

72 Why do quantitative and qualitative analyses often require different monochromator slit widths

76 Describe the differences and similarities between spontaneous and stimulated emission 79 An interference filter is constructed for isolation of nitrobenzene absorption band at 1537cm1. (a) If it is to be used on first order interference, what should be the thickness of the dielectric layer (refractive index of 1.34) (b) What other wavelength

For a weak acid (a is very small ) K. 2) a , 1) K. Ca C 3)H Ca 4) All the above 2.

3. A weak acid is 0.01 ionised in 0.1 M solution. Its ionisation constant is 1) 105 2) 106 3) 108 4) 109

4. The dissociation constant of a weak monobasic acid in 0.01 M solution is 108. What is its OH concentration 1) 106 2) 108 3) 109 4) 1010

2) 10 3) 10 4) 10 10 5. Which of the following is the best conductor of electricity 1) IM HNO, 2) IM CH,COOH 3) IM NH,OH 4) IM H,SO,

At infinite dilution, the percentage ionisation of both strong and weak electrolytes is 1) 25 6. 2)10 3) 75 4) 100

6. The dissociation constants of two acids HA, and HA, are 4.5 x 104 and 1.8 x 10 respectively. If both are having equal concentrations the relative strength of acids is 1) 52 2) 25 3) 51 4) 15

1. The first and second dissociation constants of an acid H,A are 1x10 and 5x10 respectively. The overall dissociation constant of the acid will be 1) 4x105 2) 5x10 3)0.2x10 4) 5x10

Identify, highlight and name all the functional groups present in the following biomolecules.

H HCOH HCNH, HOCH HCOH HCOH HCOH HCOH H H2OH DGlucosamina 00 o H,CH HOPO H CCCOO H HCOH H H H,NCCOH Etanolamina ()

17. Will the following reaction be spontaneous at all temperatures, spontaneous at low temperatures, spontaneous at high temperatures, or nonspontaneous at all temperatures AH 0 and AS 0

Question 4 What current is required to produce 0.78 grams per hour by the electrolytic reduction Al3 3e Al

(a) HCCCH H. H. (6) HCH HCH B AAIE 1 120 Paragraph a.) b.12Octyne

Name compounds 1 and 2 below. Include stereochemical labels. 4 each Br CI F 1. CI OH H. Br 2.

Determine the electron density.Sketch the electron density of benzene. Indicate electron rich and poor areas.Does benzene have a dipole?

Is the bond formation energy positive for any reaction?

t Clz A Hz H CI Cl2 (5) OHC CH 2 H2

Why is temperature not important once aliquots are taken?

A mixture of toluene, dichloromethane and oxylene is eluted on a nonpolar gas chromatography column. The chromatogram obtained is shown below H, CH, I3D 1000 CH, 0xylene toluene dichloromethane 500 10 15 Time (min) a) Choose ONE (1) parameter below for the above analysis and justify C18 column or capillary column i. Helium or oxygen carrier gas

The colorimeter and Beers Law are widely used in real life applications. Please go online and cite another application for this technique (aside from quantifying dyes in a solution), paste your link.

Arrhenius Bronsted Theory 1. NH, is not a base according to 1) Bronsted theory 3) Arrhenius theory 4) Lowry theory 2. HCI gas cannot act as an acid in 1) Polar solvents 3) NH, liquid 3. Which of the following is an Arrhenius acid 1) Co, 4. Arrhenius theory is failed to explain the acidic nature of 2) Lewis theory 2)Highly polar solvents

12. In the reaction NH, H,0 NH OH, the conjugate acidbase pair is 1) NH, and H,0 3) , and NH, 13. H,O OH2 H,O is 1) Arrhenius neutralisation 2) Bronsted neutralisation 2) NH, and OH 4) NH, and NH, 3) Lewis neutralisation 4) Both Lewis neutralization and Bronsted neutralisation. 14. The conjugate base of hydrazoic acid is 1) N,H, 15. Which of the

The correct answers 1) A,C 24. Which anion is strongest base 1) C,H,0 2) NO, 3) CI 4)CH,CO0 2) B,D 3) A,D 4) , 25. The strongest base of the following species is 37. Formation of dative bond is neutralizati, 1) NH, according to the following acid base theory 1) Arrhenius 3) Bronsted Lowry 4) S 26. Which of the following is the conjugate base 2)

50. In the reaction SnCl, 2CH SnCI, 2e the Lewis acid is 1) SnCl 2) SnCl, 3)SnCl, 4) SnCl, 51. Which of the following is not Lewis base 1) CH, 3) Acctone 52. Among the following is strong Lewis base 2) CH,OH 4) Sec. Amine 1) NF, 2) NCI, 3) NBr, 4) NI, 53. Which of the following is strong Lewis acid 1) K 54. The Lewis acidic strength of So, when

Explain why 6M NH 3 and not 6M NaOH solution is used when separation Fe 3+ and Al 3+ ions from Ca 2+ , Cu 2+ , and K + ions in the qualitative analysis of cations. Write appropriate chemical equations to support your conclusion.

Which of the following statements are correct I. Work and heat are state functions II. Energy is a state function III. Work and heat are not state functions (A) II and II () I and III () I only (D) II only

What mass of HI should be present in 0.250 L of solution to obtain a solution with pH value of 2.85. (A) 1.8 g (B) 0.035 g (C) 0.045 g (D) 0.055 g

Which of the following determines the direction of spontaneity (A) AG (B) AG (C) Both (A) and (B) are correct (D) Only option (B)

On increasing the temperature, the increase in conductivity of intrinsic semiconductor is due to (A) Decrease in band gap between valence band and conduction band (B) Increase in electrons in conduction band (C) Increase in negative charged electrons than positive holes in valence band (D) Increase in electrons in valence band

To find the Ce content of a solid, 4.37 g were dissolved and treated with excess iodate to precipitate Ce (IO,), The precipitate was collected, washed well, dried, and ignited to produce 0.104 g of CeO, (FM 172.114). What was the weight percent of Ce in the original solid (A) 1.84 (B) 1.49 (C) 1.94 (D) 1.74

Transition that causes to the characteristic blue color of K, Re,Cl, will be A) oo B) 77 C) T T D) 86

Molecular formula of an unknown compound is, CH0 IR values 35003200 cmand 16201550 cm Proton NMR 1.3 (6H, doublet), 3.2 (1H septet), 4.6 (1H singlet), 2.25 (3H, singlet) 6.7 (IH, singlet), 6.9 (1IH, doublet), 7.2 (IH, doublet). What is the structure of unknown compound CH3 CH3 (A) (B) HO. .CH H3C CH3 H3C CH3 H CH3 HO H2C (D) (C) H CH H3C CH3 H3C

Identify the reagent used in the following transformation OH P Q OH HO OH (A) P LIAIH, Q KMNO, () 3DNaBH, Me Q MnO, CH,Cl, 3D Q Ag,CO, on celite, PhH P NABH, CeCl,.7H,0 QMnO, CH,Cl, (C) PCeCl,.7H,O (D)

Classify the following compounds as substitutional, interstitial, or intermetallic alloy (i) PdB.15 (ii) Ag Sn (iii) Cu. ssZn034 (iv) Tio9900.01 (A) (i) Substitutional alloy, (ii) Intermetallic compound, (iii) Intermetallic alloy, (iv) Substitutional alloy (B) (i) Substitutional alloy, (ii) Intermetallic compound, (iii) Intermetallic alloy,

Consider the reaction between Fe and NCS ions. The equilibrium constant for this reaction is 620.4. Calculate the equilibrium concentration of NCS ion in a solution that contains 10.0mL of 0.05 M ferric nitrate in 1M HNO,, 2.0mL of 5.0x10 M NANCS, and 8.0mL of distilled water. Assume that all the NCS is converted to FeNCS. (A) 6.07x108 M (B) 3.04

What color would you expect to observe for a solution of Fe(ferrozine),, which has a visible absorbance maximum at 562 nm (A) orangeyellow (B) red (C) violetblue (D) bluegreen

What is the molar concentration of Ba present in 424 ppm of BaCl, 2H,0 (244.3 gmol) A. 1.73x103 M B. 0.424 M . 1.73 D. More data is required to solve the problem

The wave function for an electron in a hydrogen atom is w Ne . Here, r is the 3D distance from the distance from the nucleus to the electron and a, is Bohr radius. Calculate the normalization factor, N. (A) (7a,) (B) (1ra) (C) (za) (D) (1 za) 12 12 12

What product will be obtained for the below reaction CH3 HCCCH2 ICI CH3 CH3 () HCCCH2CI () H3CCCH2I CI CH3 CH3 () HCCCH3 (D) H,H

Which one of the following does not come under the category of systematic error (A) Instrumental error (B) Method error (C) indeterminate error (D) Personal error

Write the IUPAC name for the below compound (A) dicyclohexyl ether (B) cyclohexoxycyclohexane (C) cyclohexyl ether (D) dicyclohexoxy ether

Two moles of oxygen contained in the vessel A and two moles of hydrogen contained in the vessel B. Both vessels have equal volume and they are at same temperature. Pressure in which of these vessels is highest (A) The vessesl A (B) The vessesl B (C) Equal pressure in each vessel (D) More informati on is required to decide

Arrange the following solutions in increasing order of their pH. 0.1 M NaCl 0.1M C,HNH,Br 0.1M C,HNH,CI 0.1M NaF Use the following data to answer the question K, of HF is 6.810, K, of aniline is 4.3 x101 , K, of ethylamine is 6.41x10 (A) 0.1M C,H, NH,Cl 0.1M C,H,NH,Br 0.1 M NaCl 0.1M NaF (B) 0.1M C,H, NH,Cl 0.1M C,H,NH,Br 0.1M NaF 0.1 M NaCl

Which will be the best oxidizing agent among the following 3 I. Au 3e Au 1.50 V II. Ag e Ag III. Pb 2e Pb 0.80 V 0.13 V IV. Li e Li 3.04 V (A)I () () (D)IV

The rate constant for a second order reaction is 3.33x10 L mols. The initial concentration of the reactant is 0.5 molL. Calculate the halflife of the reaction (A)0.95 min (B) 1.95 min (C) 10 min (D)3.45 min

For the reaction N, (g) 3H, (g) 2NH, (g ), equilibrium pressures are Py, 2.6 atm, P, 5.6 atm, and PyH, 1.2 atm . Calculate the Gibbs free energy of the reaction at a NH3 H2 temperature of 298K. (A) 1.43 kJ (B) 1.43 x10 J (C) 1.4110 J (D) 4.25 x10 J

For the reaction N, (g) 3H, (g) 2NH, (g ), equilibrium pressures are Py, 2.6 atm, P, 5.6 atm, and PyH, 1.2 atm . Calculate the Gibbs free energy of the reaction at a NH3 H2 temperature of 298K. (A) 1.43 kJ (B) 1.43 x10 J (C) 1.4110 J (D) 4.25 x10 J

Calculate the percent ionization of 1.45 M aqueous acetic acid solution. K, for acetic acid is 1.8x10. (A) 0.35 (B) 0.0018 (C) 0.29 (D) 0.0051

4. For the following reactions, show all possible products and then indicate which one(s) would be major. (8 pts) NaOMe NaOMe heat

4. For the following reactions, show all possible products and then indicate which one(s) would be major. (8 pts) NaOMe NaOMe heat

Use the hypothetical standard half-cell potentials listed below to calculate the standard cell potential in units of V for the following reaction occurring in an electrochemical cell at 25C. (The equation is balanced.) 3 Cl 2 (g) + 2 Fe(s) 6 Cl(aq) + 2 Fe 3+ (aq) Cl 2 (g) + 2 e 2 Cl(aq) E = +1.73 V Fe 3+ (aq) + 3 e Fe(s) E = - 0.14 V

Choose the correct option and show a mechanism for each step.

Major products P and Q, in the given reaction sequence, are Q.No. 27 CO2Et i) 9BBN (1 eq) i) MSCI EtzN P ii) H2O2 NaOH ii) NaOH iii) H2, (Ph3P)3RHCI (A) CO2ET and HO, (B) CO2Et and HO, P (C) CO2ET and Q (D) CO2Et and Q P.

Answer the questions 1720 given the reaction of nitrous acid in water. HNO(aq) H2O() NO,(aq) H3O (aq) (6 pts) For this reaction, AGran19.09 klmol. Calculate the K, of HNO,. You must show your work for full credit. 17.

What is the name of this compound?

H3C CI CH3

(3pts) Draw the Lewis structure of H2S and H2O. Indicate the bond angle obtained with VSEPR for both molecules. Build both molecules in molcalc, and determine the angle on the webpage. Explain the discrepancy in angle for SH2.

in groundwater, the concentration of Pb was 60 ppb, what is the amount of Pb in 4 kg of groundwater?

Starch test with iodine. Theory The effect is only seen when both iodine as an element and iodide as an ion are present. Iodine, together with the iodide ion, forms a complex which dissolves in water, unlike iodine on its own. Molecular iodine (I2) reacts with iodide (I-) which is a negatively charged ion and creates an anion (I3-). The anion

Part A What is the value of AG for the reaction MCl2. 6H2O(s)= MCs) + 6H20(g) when the pressure of water vapor is 19.9 mmHg? Express your answer with the appropriate units.

When the following equation is balanced properly under basic conditions, what are the coefficients of the species shown Cl, Cr Water appears in the balanced equation as a (reactant, product, neither) with a coefficient of (Enter 0 for neither.) Which element is reduced

Ep mixed unmixed configurations Based on the PEC diagram of the octaneoctanol system shown above. Select the correct two answers O Octane and octanol will separate ( unmix) at high temperatures Octane and octanol are miscible ( mix) at high temperatures Octane octanol dominant intermolecular forces are very similar, dipoledipole and hydrogen

Propose an arrowpushing mechanism for the bromination of transstilbene. Is the product a mixture of stereoisomers Upload Choose a File

How is molecular bromine (Br) generated in the experiment Write the chemical reaction below. Why is elemental bromine not used directly in the experiment Upload Choose a File Question 9 3 pts Propose an arrowpushing mechanism for the bromination of transstilbene. Is the product a mixture of stereoisomers Upload Choose a File Question 10 3 pts

Give the major product(s) of the following reaction. KMno, H heat OH CN OH There is no reaction under these conditions or the correct product is not listed here Give the major product of the following reaction.