Chemistry Questions and Answers August 28, 2020

(b) (c) (ii) The enzyme catalyse catalyzes the decomposition of HO. The data obtained is given in the table below 0.001 0.002 0.005 Initial rate (molLS) If concentration of catalase is molL. determine Vmax, the constant Km and the turnover number, K. 6 marks Derive an expression for the rate of reversible reaction given that both reactions are of

1. (a) (i) molar shoulder maximum at 312 nm containing the two cell) of 0.726 and 0.544 at concentrations of compound A (3 marks) Compound A and B absorb in the ultraviolent region. Compound A exhibits an absorption maxima at 267 nm (a157) and a trailing at 312 nm (a12.6). Compound B has an absorption (a186) and does not absorb at 267 nm. A

2. below. (a) (i) In the determination of acetone in biological fluids the following calibration curve and unknown data obtained are given in the table Standard Mg acetone 100ml Reagent blank 2.0 4.0 6.0 8.0 10.0 Normal blood Ketonic blood Normal urine Ketonic urine (diluted) Absorbance 0.053 0.097 0.143 0.190 0.221 0.238 0.119 0.222 0.150 0.230

(a) The presence of ethylene in samples of ethane was determined by using the absorbance band of ethylene at 1443 cm . A series of standards gave the following data of ethylene Absorbance (i) (ii) 0.50 0.120 1.00 0.240 2.00 0.480 3.00 0.719 Explain how the absorbance of ethylene was determined. (4 marks) Calculate the percentage of ethylene in an

by perpendicular of curvature (iii) A singly protonated ion having MZ 375.9 is initially accelerated an electric potential of 5,000 V. After it is accelerated, it enters a homogeneous magnetic field with a strength of 4 T, applied to the path of the ions travel. Calculate the resultant radius for this ion in the magnetic field IV1 JC,1J1 Kgms

The stable Organometallic compound should Obey 18rule. Select one True False

Which of the following conditions will increase the evaporation rate Options 1) Increase in temperature of water 2) Decrease in wind speed 3) Decrease in surface area of water 4) Adding sugar to water

Which of the following isare incorrect Options 1) Solids have fixed shape and fixed volume 2) Liquids have fixed volume but not shape 3) Gases have neither a fixed shape nor volume 4) The particles have the least intermolecular space but maximum kinetic energy in liquids

The physical state of a matter depends upon Options 1) Temperature and pressure 2) Temperature 3) Pressure 4) None of these

Calculate the hydrogen ion concentration from the OH- ion concentration. [OH-]= 1.58 x 10-11 M

Predict the product(s) of the following reaction sequence Show stereochemistry, if any. Predict the product(s) of the following reaction sequence 18 CH3 1. PhMcBr 2. HO Show stereochemistry, if any.

You fill a closedtube manometer with a mineral oil whose density is 0.857 gcm. What us the pressure in mmHg when you measure a height Ah of the mineral oil equal to 87.30 mm The density of mercury at 0C is 13.592 gcm. Express your answer to two decimal places. Your Answer Answer units

Calculate the OH- ion concentration from the pOH of 10.8 ?

show ALL steps for better understanding 2. Draw the structure of X and complete the following reactions. H Lindlars cat. 1 NNH, 2. CHCHCHBr Terminal alkyne X HgSO4 HOH CH CuZn 1. BH, THF 2. HOOH

Consider the following galvanic (voltaic) cell when answering the question. 4Fe(NO3)2(aq) O2(g) 4HNO3(aq) 2HO(1) 4Fe(NO3)3(aq) Note Copying andor posting this question without the express written permission from Dr. Burke and the Department of Chemistry Biochemistry at the University of Delaware is a violation of intellectual property

Please use the values in the resources listed below instead of the textbook values. Perform the following calculations. (a) Calculate Cu (in M) in a saturated aqueous solution of CuS. (K 5.4x1037) M (b) What will Cu2 (in M) be when enough K,S has been added to (a) to make 52 0.078 M7 M (c) What will 521 (in M) be when enough Cu(NO), has been added

A buffer solution is prepared by adding 250.0 ml. of 2.0 M NaOH to 500.0 mL of 1.5 M CHCOOH (KCHCOOH LE 101 wea cil a. What are the major species present in the buffer solution 16looon Section Total Points 20 b. What salt is present in the buffer and what is the concentration e. Calculate the pH of this buffer using HendersonHasselbalch

Here is an example Zn (s) Cu (aq) Zn (aq) Cu (s) In this reaction two electrons are transferred from the solid Zn to the aqueous Cu ion. In this process the solid Zn became a Zn ion. This means that the solid Zn lost 2 electrons over the course of the reaction and went from an oxidation state of Zn(0) to an oxidation state of Zn(2). The Cu ion

Indicate which of the following chemical reaction are redox reactions a. 2PbS 30 2Pb0 250 b. CH202 CO2 2HO c. 4Fe 302Fe0 d. 2AgNO, CuCl Cu(NO)2 2AgCl e. FeCl 2NaOH Fe(OH) 2NaCl 4. Balance the following redox reaction. Remember that you need to balance both the atoms and the charge. Start by writing the oxidation number of each element above

For each of the following two reactions, predict whether the reaction is spontaneous, under standard conditions, in the direction in which it is written. Calculate Ecell for each. (a) 2 Al(s) 3 Sn(aq) 2 Al (aq) 3 Sn(aq) (b) Cd (aq) Cu(s) Cd(s) Cu (aq)

Mass of NaOH .796g and volume 200.00 mL need to find OH, NaOH snd Average NaOH clusi... A. Prepartion of NaOH solution Mass of NaOH 796 g Volume 200.00 mL B. Standardization of NaOH Mass of KHP Final burette volume Initial burette volume Volume of NaOH Moles of KHP Moles of OH OH NaOH .263 g 13.00 mL 0 mL 13.00 mL Average NaOH Standard Deviation

B Before the COVID19 pandemic the concentration of bleach was 5.25 by mass. Calculate how many mL of 0.1000 M Na2S2O3 you would need for the titration of 25.0 mL of diluted bleach (diluted in the same way as in our experiment). Show all calculations.

The temperature remains constant during the change of state due to Options 1) Latent heat is used in the change of states 2) Force of attraction between particles 3) Both 1 and 2 4) None of these

300 K on Celsius scale will be fillinteger C

The naphthalene balls disappear with time without leaving any solid because of Options 1) Sublimation 2) Condensation 3) Evaporation 4) All of the above

A diver can cut through water in a swimming pool. Which property of matter does this observation show Options 1) The matter is made up of particles 2) Particles of matter have spaces between them 3) Both 1 and 2 4) None of these

The order of increasing density of cotton, water, honey, iron, and exhaust from a chimney is Options 1) Exhaust from chimney cotton water honey iron 3) Iron

A gas fills the vessel in which it is kept because of Options 1) Low force of attraction 2) Strong force of attraction 3) Both 1 and 2 4) All of the above

The gases exert pressure on the walls of the container due to Options 1) Weak intermolecular interactions 2) Strong intermolecular interaction 3) They do not exert pressure 4) None of these

Liquids generally have lower density as compared to solids because Options 1) Liquid particles can move about freely 2) Packed loosely 3) Both 1 and 2 4) None of these

At 250C, water in the form of Options 1) Solid 2) Liquid 3) Steam,4) Liquid and vapour

Which of the following acids is are used in the reaction of ethanol to form ethene and the formation of esters Options 1) Concentrated nitric acid 2) Concentrated sulphuric acid 3) Acetic acid 4) Propanoic acid

Which of the following isare problems related to the usage of detergents Options 1) Detergents are not biodegradable 2) The phosphates in detergents act as nutrients for algae in water bodies 3) They endanger the aquatic animal life 4) All of the above

Which of the following is a are the ill effects of alcohol on the body Options 1) It affects the central nervous system 2) It reduces metabolism 3) Angry and rude behaviour 4) All of the above

Initiatives like Save life, do not drink is are essential because Options 1) Alcohol is not harmful to the body 2) Alcohol is addictive 3) Consumption of alcohol leads to increase in crimes in the society 4) Both 2 and 3

The catalyst used in hydrogenation reaction is Options 1) Nickel 2) Gold 3) Carbon 4) Chlorine

Which of the following isare bad for human health Options 1) Saturated triglycerides 2) Polyunsaturated fatty acids 3) Saturated fatty acids 4) Both 1 and 3

Which of the following changes is are effects of incomplete combustion of LPG Options 1) Yellow and sooty flame 2) Blackcoloured deposition on cooking vessels 3) Environmental pollution 4) All of the above

The incomplete combustion of LPG fuel leads to the formation of oxides of Options 1) Sulphur 2) Nitrogen 3) Both of the above 4) None of the above

The element which forms the largest number of compounds is Options 1) Gold 2) Argon 3) Copper 4) Carbon

The molecular masses of HCHO and CH,CHO are fillnumberg and fillnumber g respectively.

If the water contains calcium carbonate, which of the following can be used to clean clothes in it Options 1) Soap 2) Detergents 3) Both of them can be used 4) None of them can be used

A saturated compound X on combustion gives two molecules of carbon dioxide and 3 molecules of water. The compound X is Options 1) Ethane 2) Propyne 3) Butyne 4) Methane

Ethanol reacts with sodium which is stored in kerosene to give hydrogen gas and a compound Y. The compound Y is Options 1) Sodium hydroxide 2) Sodium ethoxide 3) Sodium carbonate 4) Sodium bicarbonate

The number of covalent bonds present in propane are fillinteger).

A compound X with molecular formula C4H0 burns with a blue flame and is a component of LPG. The compound X is Options 1) Butane 2) Butene 3) Butyne 4) Propane

Which of the following products isare formed when ethanoic acid reacts with ethanol Options 1) Sodium acetate and carbon dioxide 2) Butane and water 3) Ester and water 4) Ester and carbon dioxide

Which of the Options following is not a property of ethanol 1) It has a pleasant odour 2) Ethanol shows no effect on litmus paper 3) Ethanol gives a positive NaHCO3 test 4) All of the above are correct

Methane gets converted to chloromethane in the presence of Options 1) Ultraviolet light 2) Temperatures above 300C 3) Both of the above are correct 4) None of the above is correct

(d) Consider the following multiplication table for the C4 point group Ov 343536666 C E E C C C Ov 6 Od Od 3333 6666 C4 C4 C C3 E C C C E C4 Ov Gy o Gd C C3 E C4 C 6666 Ov ov Ov od 533 E C C4 od Ov o C E C4 C 64 Oy Od C E C od Gd Gy C E (i) Construct the multiplication table for each of the nontrivial subgroups of the C point group. (8 marks)

(b) Consider the structures of the three isomers of IF3O Determine the symmetry elements and the point group of each isomer (6 marks) F OITIO F O COMF F II F F III

(a) Determine the fundamental vibrational modes of BC13 (D3h) that are infrared and Raman active (10 marks) (b) Determine the atomic orbitals that Xe can use to form hybrid orbitals in XeF4 (D4h) marks) (10

e) Write the mechanism of bromination of pyridine Br 1. SO3HSO4 2. Br 3. NaCO3 N (6 marks)

a) Give the IUPAC names of the following structures i) v) ii) Bri 2. POCI 3. H2O Br b) Write the mechanism of the following reaction 1. (CH3)2NCHO iv) (5 marks) (6 marks)

c) Write the mechanism of the Guareschi synthesis of unsymmetrical pyridines from the reaction between a Bdicarbonyl compound and a enamimocarbonyl compound (5 marks) NH 2HO N

(c) The following data was obtained for a water sample. All of the tests were performed using a sample size of 100mL. Tare mass of evaporating dish 52.1533 g Mass of evaporating dish plus residue after evaporation at 105 C 52.1890 g Mass of evaporating dish plus residue after ignition at 550 C 52.1863 g Tare mass of Whatman GFC filter 1.5413 g

Ethanol reacts with sodium and forms two products which are Options 1) Sodium ethanoate and hydrogen 2) Sodium ethanoate and oxygen 3) Sodium ethoxide and hydrogen 4) Sodium ethoxide and oxygen

(b) A bioassay was carried out on shrimp in aquaria and the following data obtained after 24 hours Number of Shrimp Surviving (of 200aquarium) 200 164 124 72 22 0 Concentration in Aquarium Water (gl) 11.0 14.5 19.1 21.9 30.2 57.5 Estimate graphically the LC 50 and LC 80 values (6 marks)

(iii) found formation of When a sample of 4heptanone was irradiated for 100 sec with 313 nm radiation with a power output of 50W under conditions of total absorption, it was that 2.8 mmol CH, was formed. Calculate the quantum yield for the ethane 20 marks

Five laboratories (A, B, C, D and E) determined the concentration of lead naturally occurring in soils in mgkg and obtained the following results as shown in the table below. Laboratories A B C D E Replicate 1 22 29 17 16 30 Replicate 2 22 18 18 19 25 Replicate 3 18 21 19 18 24 Replicate 4 17 20 23 18 27 Perform analyse of variance and test if the

An analytical chemist claims that it is faster to test water quality using analytical kit A than kit B. To test the claim, eight technician of proven ability were assigned each to the two kits and the time taken to carry out the analysis was recorded as follows Technicia 1 n Kit A Kit B 21 29 2 33 39 3 35 39 4 17 23 5 27 23 6 33 37 7 31 29 8 41 43

c) Calculate the number of photons emitted by a 200 W yellow lamp in 2.0 seconds. Take the wavelength of yellow light as 560 nm and assume 100 percent efficiency (h 6.626 x 10 34 JS, C 2.998 x 10 8 ms1) (4mks)

b) For a standing wave, such as a vibrating string of wavelength (2), whose amplitude at any point along x may be described by a function f(x), it can be shown that 42 f(x) df(x) dr Using the equation above, derive the Schrdinger wave equation (5mks),74 8xm h (EV) (

(b) Phosphorus in urine can be determined by treating with molybdenum (VI) and then reducing the phosphomolybdatewith aminaphtholsulfonic acid to give the characteristic molybdenum blue colour. This absorbs at 690 nm. A patient excreted 1270 ml urine in 24h and the pH of the urine was 6.5. A 1.00 ml a aliquot of the urine was treated with

QUESTION THREE (20 MARKS) (a) (i) (experimental marks double marks If chloroform (trichloromethane) exhibits an infrared peak at 3018 cm due to the CH stretching vibration, calculate the wave number of the absorption band corresponding to the CD stretching vibration in deuterochloroform value 2253 cm) (ii) A ketone possesses an absorption band

(b) (i) The following experiment is used to determine the vinyl acetate (VA) level in an ethylene vinyl acetate (EVA) commercial packaging film infrared spectra packaging films with known vinyl acetate contents are recorded. The absorbance peak at 1030 cm used to determine the content of the vinyl acetate was measured by the baseline method

The molecular inversion of the (Cp)Be, in which exchange between 1 and 5 coordination modes can be shown only in the solid state. Select one True False

Is it true that when ethanoic acid reacts with sodium metal, it results in the formation of ethanol and hydrogen gas Options 1) True 2) False

H HCH H Is it true that the given diagram is an electron dot structure of methane Options 1) True 2) False

Is it true that a halogenation reaction is a type of an addition reaction Options 1) True 2) False

The solubility of ammonium chloride in water at different temperatures is given below Temperature (in degree celsius) 10, 20, 40, 60, 80 Solubility (in grams) 24, 37, 41, 55, 66 The mass of ammonium chloride needed to make a saturated solution of ammonium chloride in 50g of water at 40C is fillnumber g.

Naphthalene and common salt can be separated with the help of Options 1) Handpicking 2) Evaporation 3) Sublimation 4) Condensation

Is it true that the sublimation process can separate anthracene and copper sulphate Options 1) True 2) False

Consider the PtC14 ion which belong to the D4h point group (a) Determine the atomic orbitals on platinum that are used to form obonds with chlorine atoms in the PtC14ion. (12 marks) (b) Determine the SALCs that are required to form PtCl obonds in the PtC14ion. (4 marks) (c) Sketch the molecular orbital diagram for the PtCl4ion. (4 marks)

(d) A solution of Ni(HO) is green and paramagnetic (u 2.90 BM), whereas a solution of Ni(CN)4 is colorless and diamagnetic. Give a qualitative explanation for these observations (2 Marks) (e) Calculate the ligand field stability energy (LFSE) and the magnetic susceptibility of the following species (3 Marks) (i) Fe(CN)64 (ii) CoC14 (iii) IrBr4 (f)

QUESTION THREE 20 MARKS (a) Determine the ground state term for each of the following configurations (i) d (low spin, Oh) (ii) d (highspin, Oh) (3 Marks)

(a) Construct an Orgel diagram for Ni(HO) and write the possible electronic transitions. (3 Marks) (b) Estimate the values of A, and the Racah parameter, B, for the Ni(HO) complex if it has absorption bands at 8,500, 15,400 and 26,000cm (5 Marks) (c) Draw a well labelled molecular orbital energy diagram for obonding in Co(NH3)6 complex and

(c) The electronic spectrum of a complex TiL6 (L neutral monodentate ligand) shows a weak ( 7 dm mol cm) absorption with a shoulder at Amax 19, 200 cm. Explain the origin of this absorption and the shoulder (3 Marks)

(e) Determine the atomic orbitals that nickel can use for obonding in the Ni(CN)4 complex and sketch the molecular orbital diagram (8 Marks)

Organometallic compound dont have a covalent bond. Select one True False

Spectrophotometric method for the quantitative analysis of in blood uses as an internal standard. A standard containing 1.75 pp b and 2.25 ppb yields a ratio of (SA/sis of 2.37. A sample of blood is spiked with the same concentration of giving a signal ratio of 1.80. Determine the concentration of in the sample.

2 pb

(i) A simultaneous determination for cobalt and nickel can be based on absorption by their respective 8 hydroxyquinolmol complexes. Molar absorption corresponding to their absorption maxima are as follows. Molar absorptivity , 365nm 700nm Co 3529 428.9 Ni 3228 10.2 Calculate the molar concentration of nickel and cobalt in each of the following

Ammonia has been studied as an alternative clean fuel for internal combustion engines, since its reaction with oxygen produces only nitrogen and water vapor, and in the liquid form it is easily transported. An industrial chemist studying this reaction fills a 125. L. tank with 20. mol of ammonia gas and 11. mol of oxygen gas, and when the mixture

Calculate the ration of sodium atoms in the 3p excited to the number in the ground state at 2500 and 2600k { h= 6.6261 x JS, C = 2.998 x m/s, 1 nm = m, the statistical weights for the 3s and 3p quantum states are 2 and 6 respectively. Boltzmanns constant k = 1.38 x . [2 marks]

1023

Which of the following will give a positive NaHCO3 test Options 1) Ethanol 2) Ethanoic acid 3) Both of the above 4) None of the above

The dehydration of ethanol results in the formation of Options 1) Methane 2) Ethane 3) Ethene 4) Butyne

The molecules of soap are the potassium or sodium salts of a long chain fillregular acids.

Which of the following is are responsible for causing the hardness of water Options 1) Calcium carbonate 2) Magnesium carbonate 3) Sodium nitrate 4) Both 1 and 2

Which of the following isare not a property of ethanoic acid Options 1) It is blue in colour 2) It has a sour taste and a pungent odour 3) It is corrosive 4) It forms esters on reaction with alcohols and sulphuric acid

The saponification of simple fillregular leads to the formation of soap.

A compound X is used widely as a preservative in pickles. The name of the compound is Options 1) Ethanol 2) Propane 3) Ethanoic Acid 4) None of the above

The reaction which involves the conversion of ethanoic acid from ethanol isare Options 1) Dehydration reaction 2) Oxidation reaction 3) Reduction reaction 4) Both 2 and 3

When ethanoic acid and washing soda react, which of the following products are not formed Options 1) Carbon Dioxide CO 2) Sodium ethanoate CHCOONa 3) Water HO 4) Hydrogen chloride HCI

QUESTION TWO 20 MARKS (a) The AX4 molecules can either be tetrahedral (Ta) or square planar (D4h). Describe how group theoretical analysis of vibrational (IR and Raman) spectroscopy of an AX4 molecule can be used to establish its molecular geometry (12 marks)

(b) Determine the atomic orbitals of the indium atom that can used to form o hybrid orbitals for the InCl2 (C4) ion. (6 marks)

A compound formed when ethanol is heated in excess of concentrated sulphuric acid at 443K is fillregular).

KMnO4 is used as an fillregular agent in oxidation reactions.

A compound fillregular) with molecular formula CHO on oxidation gives an acid fillregular). Doctors use the first compound for sterilisation of skin.

Is it true that alcohol and carboxylic acids react to form an ester Options 1) True 2) False

X Alk. KMnO4 Heat Y . In this reaction X is fillregular) and Y is fillregular).