Chemistry Questions and Answers June 06, 2020

Here below is shown the Ellingham diagrams for some selected dblock elements. 250 Cuo CoCo FeO CCO SO CCO CaO 500 1000 1500 2000 2800 Temperaturec Select the correct statement(s). explaining your reason(s) a) Above 710 C, C is a better reducing agent than CO b) For M(s) 02 MO(s), AG RT In (pO2) c) All the metal oxides can decompose at

A decapeptide undergoes partial hydrolysis to give peptides whose amino acid compositions are shown. Reaction of the intact decapeptide with Edmans reagent releases PTHGly. What is the sequence of the decapeptide 1. Ala, Trp 2. Val, Pro, Asp 3. Pro, Val 4. Ala, Glu 5. Trp. Ala, Arg 6. Arg. Gly 7. Glu, Ala, Leu 8. Met, Pro. Leu, Glu Spell out the

Which of the following compounds will be MORE soluble in acidic conditions than in pH neutral conditions ONANO, O SrCO, O PbF, O LINO, ONaC O FeCly O Nal O CalCH,O

Which halide is least reactive towards Sy2 reactions O a. tertbutyl bromide O b. secbutyl bromide Oc. isopropyl bromide O d. methyl bromide O e. cyclohexyl bromide

The thiourea in a 1.455 g sample of organic material was extracted into a dilute sulfuric acid solution and titrated with 37.31 mL of 0.009372 M Hg+ via reaction: 4(NH2)2CS + Hg+ [(NH2)2CS]4 Hg2+ (7) Is this an example of a total analysis technique or concentration technique? Explain. (8) Calculate the percent (NH)2CS (76.12 g/mol) in the sample.

g of water is at 25.0 C. If a quantity 10.0 of metal at 80 C is placed in the in the water, the final temperature of the water and the metal is 35 C. The specific heat of the metal is 7.128 Jg C and the specific heat of the water is 4.148 Jg C. Calculate the mass of the metal . 1.3 b. 1.7 gO . 3.9 d. 2.3 O

When 13.8 mL of 0.870 M lead(II) nitrate reacts with 90.0 ml of 0.777 M sodium chloride, 0.579 kJ of heat is released at constant pressure. What is AH for this reaction Pb(NO3)2(aq) 2NACI(aq) PbCl2( s) 2NANO3(aq) a. 48.3 kJ b. 57.6 kJ . 39.9 kJ d. 31.6 kJ . 23.3 kJ

The density of O2 gas at 16C and 1.27 atm is O a. 2.36 gL. O b. 1.98 gL. O c. 1.50 gL. O d. 1.71 gL. O e. 1.61 gL. ,The density of O2 gas at 16C and 1.27 atm is O a. 2.36 gL. O b. 1.98 gL. O c. 1.50 gL. O d. 1.71 gL. O e. 1.61 gL.

A scientist is experimenting with a reaction of hydrocarbon compound B in the presence of UV light. In his observation, he found that compound B releases reddish-brown gas when undergoing halogenation process to produce compound D. Different experiment was carried out for compound B and the result showed that the products obtained were geometrical

a) During the meeting between Mrs Sasu and Mr Stir, Mr Stir said that SAG intends to launch a derivative claim under the Companies Act 2019. Mrs Sasu is not familiar with this term. Provide a briefing note for Mrs Sasu explaining what a derivative claim is, whether SAG can launch a claim and whether there are any statutory defences and processes

Which reaction conditions will achieve the following conversion CH3 CH3 cCHCH3 CHCHCH3 Br O a. 1) PCC then HBrZnBr2 O b.1) BH3 2) H2O2HO then HBr O c.1) H20H 2) Cro3H then HBr . O d. 1) PB13 then H30 O e. 1) H20H then HBr

What is the oxidation number of C in HCOO, is . b. 1 . 2 d. 0 . 2 ,The density of NO gas at 16C and 1.27 atm is O a 1.61 gL. O b.1.71 gL. O c. 1.98 gL. O d. 2.36 gL O e. 1.50 gL.

What is the volume occupied by a mixture of 0.774 mol of N2 and 0.774 mol of O2 gases at 1.16 atm and 25.6C . 36.5 L b. 31.6 L C. 35.2 L Od. 32.8 L e. 33.9 L

In the reaction Pa 10 Cl2(g) 4PCI5(5) The reducing agent is Select one O a. Cl2 O b. PCI5 C. P O d. Cl ,Indicate the reaction(s) where the Pb(IV)oxide is reduced I) PbO2 4HE PF4 2H20 II) PbO2 Cu Pbo Cuo III) PbO2 2H2 Pb 2H2O Select one O a. I O b. II O c. II O d. III O e. IlIII

If 23.2 ml of NaOH solution is required to neutralize 0.123 g of KHP (molar mass 204.2 gmol), then the molarity of NaOH is Select one a. 0.026 b. 2.60 c. 0.922 d. 0.014 ,Arrange of the following chemicals B U Z in order of decreasing (highesttolowest) reactivity on the basis of the following reactions B z B Z U z no reaction Select one a. B Z

Which of the following reactions does not occur Select one . 2CI O b. 2Br Cl2 O c. Cl2 21 O d. Br2 21 2 ,Given the following reaction NacI AGNO3 AgCI NANO3 Which of the following statements is correct. Select one a. AGNO3 is insoluble in water b. The net ionic equation is Na NaNO3(s) (aq) NO3 (aq) c. The net ionic equation is Ag Cl(aq)

When SO2 gas dissolved in water, the resulting solution is Select one O a. acidic b. basic O C. neutral O d. does not change ,The density (gml) of 0.1 Liter of gasoline whith mass 30.5 g is Select one O a. 3.15 O b. 31.5 O c. 3.28 O d. 0.305

When 13.59 g of PTSO4.X H20 is burned, 10.87 g of white product is obtaining. Calculate mole of hydrated salt O 363 345 327 O 309 Next

Below is the generic skeleton chemical equation for a combustion reaction. A,B, C, AC2 B,C What is the balanced equation for the combustion reaction

Analysis of pesticides can be divided into two categories. Analysis of pesticide formulations and residue analysis. For each of the category, mention analytical techniques which are appropriate for analysis and give the reason for the answers.

For a spherical sodium particle of 25 nm radius crystalizing in a BCC structure having a density of 1.51 g/cm^3, estimate the surface energy of the particle. b. Estimate the surface energy of {100},{110} and {111} surfaces of an FCC lattice with bond strength of 7.97 eV and lattice parameter of 4.2 . Also compare the energies.

Complete the following nuclear fission equation U inKr 3 n Select one 138 O a. 56Ba 141 b. 36Ba 139 O C. 56Ba 140 O d. 56

How many cubic millimeters are present in 0.923 m3?

Provide a complete arrowpushing mechanism for the following transformations (lone pairs, formal charge and curved arrows). H. H H H. 0.

What is the complete name of the following sugar OH OH Write out the words alpha and beta. This question is casesensitive. Capitalize only the configuration desiguation, D or L, example betaDglucopyranose.

When 3.14 g of Compound X is completely combusted, 6.91 g of CO, and 2.26 g of H,O form. The molecular formula of Compound X is b. C,H,,O. a. C,H6. c. C,H,O, d. C,H,O,.

Write an assembly language procedure named equalsIgnoreCase, which receives two strings and their sizes, and returns true if the two strings contain the same characters irrespective of the case. For example, for strings {aBc} and {Abc} the function returns true, but for {aBc} and {aB}, or {aBc} and {Xbz}, the function returns false. Write a

5. Indigo is a blue dye H. H. a) Draw the line structure for indigo. b) Place an asterisk next to any chiral carbon atoms in your structure (if there are any). Explain your choice in 12 sentences. c) Label all of the functional groups in your indigo molecule. d) If you were trying to use titration to quantify the amount of indigo in a sample,

Fill in the table below Name Structure Propyl 3 methylbutanoate 2hexyne HO.

2. Nickelcadmium batteries employ the following reaction Cd (s) NiO(OH) (s) Cd(OH)2 (s) Ni(OH)2 (s) a) Balance this redox reaction in basic solution. b) Use line notation to represent this reaction.

3. The CAS9 enzyme (shown in red in the image below) is able to target and cut out specific DNA sequences.. a) What are the molecular building blocks of CAS9 b) Explain in a few sentences how these building blocks come together to make something as complex and functional as CAS9. What types of interactions hold CAS9 together What are the molecular

4. Cucumber aldehyde is responsible for the aroma of cucumbers CH3 a) Which functional group is produced with cucumber aldehyde is oxidized b) Which functional group is produced when cucumber aldehyde is reduced c) Write a chemical equation for the complete hydrogenation of cucumber aldehyde. d) What volume of hydrogen gas (at STP) is required to

Give the Reagents. KMN04 O 1) LIAIH4, 2) H3O O periodinane O 1) MgCI, 2) H3O

Aspartame (structure shown below) is an artificial sweetener marketed under Equal and Nutrasweet. In the body, aspartame is hydrolyzed (under acidic condition) to produce methanol, aspartic acid and phenylalanine. Predict the structures of aspartic acid and phenylalanine by proposing a( stepbystep arrow pushing mechanism. (8 pts.) NH, 0 Aspartame

2. Which is the most acidic hydrogen in the following compound Provide a brief explanation. H II IV H H.

8. Propose an efficient synthesis for the following transformation. Hint You will need to use the ozonolysis reaction.

For which of the following we CAN NOT draw a stable Lewis structure 4 O All of the above have stable Lewis structures O PCI5 O NC15 SF6 ,XeH2 has geometry and the central atom has lone pairs Bent (Angular), 3 Bent (Angular), 4 Linear , 3 Trigonal Planar, 2

In this virtual lab exercise, multiple products were obtained, and distillation was performed to try to isolate only one of those products. The products that were obtained were methyl 3-oxopentanoate, methyl acetylacetanoate, methyl 2-methyl-3-oxobutanoate, and methyl 2-methyl-3-oxopentanoate 1. Explain why all of these products are obtained,

A 0.06 g of the NaCl sample (FM 58.44) was treated with 15.00 mL of standard 0.120 M AGNO, (FM 169.872) solution. The excess silver was titrated with standard 0.211 M KSCN (FM 97.182) solution, requiring 3.08 mL to reach the red Fe(SCN) end point. Calculate of chloride (AM 35.5) in the NaCl sample. NaCl(aq) AGNO (aq)A9CI(s) NANO (aq)

What is the volume occupied by a mixture of 0.774 mol of N2 and 0.774 mol of O2 gases at 1.16 atm and 25.6C a. 36.5 L b. 31.6 L C. 35.2 L d. 32.8 L e. 33.9 L

8.00 mL of vinegar solution is titrated with 39.0 mL of 0.20 M NaOH. Calculate the mass percent of acetic acid (Molar mass 60.05 gmol) in vinegar. Assume the density of the vinegar is 1.00 gml. O a. 7.81 O b. 5.20 O c. 6.69 O d. 9.37 e. 5.85 ,Given that 2H202(1)2H20(g) O2(g) AH 176.0 kJ 2H2(g) 02(g) 2H20(g) AH 548.8 kJ. Use Hesss law to

When 0.250 g of iron (atomic weight 55.85 gmol) is burned, 0.341 g of iron oxide is obtained. What is the mass percent of iron in the iron oxide Given that the atomic weight of Oxygen 16.00 gmol. 3D O a. 83.1 O b. 77.9 O c. 75.5 d. 73.3 e. 80.4 ,In a calorimeter calibration experiment, a sample of 55.50 g of water at 55.00 C is added to a

The molar mass of a volatile liquid is 94.00 gmol, and its vapor oat 98.50 C and 740.0 torr. If the mass of vapor is 0.5450 g, calculate the volume of the vapor. (1 atm 760 torr, R0.0821 L.atm.molK1) D O a. 200.4 mL O b. 107.3 mL O c. 178.9 mL O d. 181.6 mL O e. 157.4 mL

Given that 2H2O2(1) 2H20(g) O2(g) AH 176.0 kJ 2H2(g) O2(g) 2H20(g) AH 548.8 kJ. Use Hesss law to calculate AH for the reaction H2O2(1) H2(g) O2(g). O a. 196.4 kJmol. O b. 181.4 kJmol O C. 176.4 kJmol O d. 186.4 kJmol O e. 191.4 kJmol

The label of a stock bottle of aqueous hydrochloric acid indicates that the solution is 36.596 HCI by mass and has a density of 1.18 gcm. What is the molarity of the solution Oa. 14.8 Ob. 17.4 O. 5.71 Od. 6.2 e. 11.8

What is the volume occupied by 25.0 g acetylene gas (C2H2) at 515 Torr and23 C Oa 12L 117.8L Oc 21.6 L Od 29.1 L Oe 26.2L

What volume (mL) of 0.35 M NAOH is required to neutralize 50.00 ml of 2.50 M HCI in an acidbase titration O a. 612 mL O b. 50 mL O c. 179 mL d. 225 mL e. 357 mL

What is the atomic weight of an atom whose isotopes are 97.234 amu (abundance 75.52 96), 98.032 amu (abundance 21.02), and 99.563 amu (abundance 3.46 96) O a. 97.909 Ob. 97.517 Oc. 97.482 O d. 98.045 O e. 97.612

Which of the following compounds has the E configuration of the double bond CH,NH, CN NH2 CIH,C COOH BrH,CH,C OCH3 Br CI

The alkyne, which gives two ketones upon hydration, is O H3CH2CC CH O H3CC CCH3 O HCH2CCE ECCH,CH3 O H3CH,CH,CC CCH3 etivity Jump to.. ements ,The best reagent or sequence of reagents to accomplish the following reaction is H. CH3 H3CC CH C H. H3C NANH2 followed by CH3CI then Li NH3(1) O Li NH3(1) then NANH2 followed by CH3BR O H2 Lindlars

Which of the following compounds has the Z configuration of the double bond CHO HN. CH2NH2 CIH2C COOH BrH,CH2C OCH3 CI Br CN NH2 ,Which of the following has the S configuration H3CC HOH,C OCH3 HCO HOOC C. H CH2OH H . CEN HC NH2 H3C

The following pair of structures are classified as CHO H3C CI CI CH3 and H3C CI CI CH3 H,OH H,OH O Identical O Constitutional isomers O Diastereomers O Enantiomers

What Is the IUPAC name of the followlng compound CI Br O 1Bromo5chlorocyclopentene O 2Chloro1bromocyclopentene 2Bromo3chlorocyclopentene O 2Bromo1chlorocyclopentene 1Bromo2chlorocyclopentene

Which of the following compounds is chiral O HO OH HO Hi CI Br CI CH,CH,CHCH,CH, Br. CI

The best reagent or sequence of reagents to accomplish the following reaction is H. CH3 H3CC CH H. H3C H2 Lindlars catalyst NANH2 followed by CH3CI then Li NH3() NANH2 followed by CH3B then H2 Pt Li NH30) then NANH, followed by CH3B. ,Which alkene produces the least amount of heat upon hydrogenation

A famous and anonymous axiom about quality is: We never have time to do it right the first time but, we always have time to do it over. How and where in the project plan, would you build into your plan a method to eliminate or at least, minimize the potential consequences of this axiom (sometimes life threatening for example, thinking about the

How many of the following species can disproportionate under suitable conditions N2O3, NO2, N,O5, P406, P4O10, HPO2,

P4010 contain some longer and shorter P 0 bonds. The difference between the longer and shorter bonds is

The difference in the number of P P bonds and the number of PPP bond angles in P4 molecule is

The number of sp atoms in cyclic trimetaphosphoric acid is ackspace 7 8 9 4 5 6 1 2 3 Clear All

A solid compound, of general formula M . n(CH3OH), with MW(M) = 790.48 g/mol, is heated and the TGA analyses show the first decomposition between 50 and 80 C correspondings to a loss of 10.83% (CH3OH). Determine n, the number of moles of CH3OH. The compound, whose formula is PtCl2P2CyHz. nCH3OH was analyzed with Elemental Analyses, providing the

What is the objective? An experiment measuring density and viscosity.

What is the theory? An experiment measuring density and viscosity.

Find Density of fluids Weight of the fluid In (g) Fluid volume Density of fluid (kgm) (ml) Shampoo 53 up 50 Shampoo 90cm

Listed below are several hypothetical nucleophilic substitution reactions. None is synthetically useful because the product indicated is not formed at an appreciable rate. In each case provide an explanation for the failure of the reaction to take place as indicated. () OH CH, OH (b) OH X H () OH X HO. (d) CN X Br Br CN (e) NH, CH,OCH,

What is the major product for the following reaction t BUOH, tBUOK I II III IV O II O I and III IV

Cycloheptatriene (A) is very stable. Cyclopentadienone (B) by contrast is quite unstable and rapidly undergoes a Diels-Alder reaction with itself. Propose an explanation for the different stabilities of these two compounds.

Suggest a structure the in missing entries CH, CH . CH,C CH,CH,COCCH CH CH, H, heat b. CH,CH,CH,CH,COOH CH,CH,CH,CH,OH CH, O CH, H. heat c. CH,CCH,COCH,CH,CCH, H,O CH, CH, OH, heat d. CH,CH,COCH, H,0

The harmonic oscillator (with potential V(x) 0.5 k x) was perturbed so that the force constant increases from k to (1 e)k , where e is a positive fraction. The first order perturbation theory was used to calculate the energy of perturbed system. The ratio of energies (EE) and ratio of frequencies (vv) after and before the perturbation are,

2 If usng a large ball, is the viscosity will be change Why 3 If the temperature increased, what will happen about the dynamic viscosity 4 What is the shortcoming of this method

Predict the product for the following reaction. H. NAOHH,O IV OII O IV O no reaction

Predict the product for the following reaction. H. NAOHH,O IV OII O IV O no reaction

Provide the reagents necessary to carry out the following conversion. OH OH O LIAIH4 NABH4 DIBALH BH3THF Cand D

Predict the product for the following reaction. SOCI2 , CHCH2OH pyridine pyridine O ethyl 3methylbutanoate O ethyl 2methylpropanoate O isobutyl ethanoate O 5methyl3hexanone O None of these

For the following reaction, which of the following change(s) in the IR spectrum is consistent with conversion of the reactant to the product Br absorption at 3300 3400 cm1 should disappear absorption at 3300 3400 cm1 and 1100 cm1 should disappear O absorption at 1100 cm1 should disappear, a new absorption at 3100 cm1 should appear O absorption

Propose a reasonable mechanism for the following reaction. NH2 H30 NH H.

What is the major product 1) C, hu 2) NaOEt, EIOH 3) Hg(OAc)2, H20 4) NABH. 5) Br2, FeBr, OH . Br OH . Br Br . Br OH D.

Consider the sp hybrid orbital of the Hatom 1 spx (2s 2px) (a) Find the expectation value of L7 in the spx state in units of h. That is, find ,(b) Find the expectation value of L2 in the spx. state in units of h2. That is, find h ,(c) Find the expectation value of the Hamiltonian H in the spx state in units of RH. That is, find RH

The table below gives the Lennard-Jones parameters for some different substances. He Ne H2 O2 N2 CH4 CO2 Cl2 [nm] 0.26 0.28 0.30 0.43 0.37 0.38 0.40 0.41 [1022 J] 1.41 4.93 4.60 15.6 12.6 18.9 26.2 49.3 (a) In Lennard-Jones theory, the molar enthalpy of vaporisation is estimated as Hvap = 1/2 nL, where L = 6.02 1023 mol1 is Avogadros number.

Complete the following basesubstitution reactions. Indicate the color changes for reactants and products (H)2Dye OH HDye OH Fe(III)H,O NCS Fe(III)NCS H,0 Fe(III)Acetone NCS

REACTIONS Give the structure of the major organic product(s) expected from each of the following reactions, No Reaction may be an acceptable answer. Assume that standard workup procedures are used after each reaction unless otherwise noted. 1. a) 1) H 2) PCC b) 1) (Ph),PCH 2) H,0, H,0 3) CH, c) 1a) LDA 1b) o (P. CH,OH (1 equiv) H (cat) e) H,CO.

Draw the intermediate that would form based on the following curved arrows. CH3 H3C

Which of the following reactions will not yield a ketone product AlCl . CH3 1) LIOHCHCH,Li . 2)HOHO C. 1) CHCH,MgBr D. 2) H 3) HO

2H2O2 4aminoantipyrine Quinoneimine HCI 4H2O 4 chlorophenol this reaction is involved in measuring the following analyte AAlbumin,Uricacid,Glucose ,TG0 BProtein, Albumin,Uricacid,Glucose O CUric acid,Glucose, TG, HDL Dall the above O ENone of the above O

choosing density of water in calibration of volumetric glasswares depends on knowing Select one O a mass Ob. Temperature Oc Volume Od color of solution

1. Draw the structure of the major products of the following reactions O (1) DMSO, (COCI)2 (2) Et,N A. H,CrO H. . (1) KMNO,, HO, A OH (2) H,O .

6. Draw the structures of the products A, B, C and D. NAOH TSCI (S,2) B Pyridine (R)2Butanol TSCI LICI D Pyridine

Based on the buffer you have identified in the previous step, the molar mass of the salt used to prepare this buffer is This unknown buffer is considered as buffer, according to its pH. This buffer consists of and salt of its conjugate When HCl is added to the buffer solution, which component of the buffer will react with the H,0 added The pH

Preparation of buffer solution and identification of unknown buffer solution Part I Determination of K, of the buffer solution Solution pH Initial After adding 2 mL HCI After adding 2 ml NaOH Distilled water 71 12.5 2.2 Unknown buffer 438 38 4.9 Use the table above and the data given in the manual to determine the following pH of the unknown

Determine the percent chloride composition of a sample in terms of magnesium chloride if a 0.6538 g sample was titrated with 50.0 mL of 0.1125 M silver nitrate solution and the excess silver ion was back titrated by 9.32 mL of 0.1005 M ammonium thiocyanate solution. Write the balanced chemical equation. Atomic Masses: H 1 C 4 O 16 N 14 Na 23

Name the following compounds CH3 F HO

(a) According to the epoxyamine reaction, determine the functionality of the diglycidyl ether of bisphenol A (1) in a hardening reaction with diethylene triamine (II). CH3 CH,CHCH,O 0CH2 CHCH2 CH3 (I) (b) What is the functionality of (II) in this reaction Ans. (a) 2 (b) 5 H2NCH2CH2NHCH,CH,NH2 (II)

Which answer best describes why Dr. Martin Luther King responded almost immediately by organizing a bus boycott after the Rosa Parks incident in Montgomery, AL O The boycott resulted from his civil rights strategy. O The boycott resulted from his opportunistic mindset. O Dr. King was using the Waterline Principle as a means to determine whether

A 0.100 molL aqueous solution of CH3NH2 has a pH of 11.82 at 25C. Calculate the base constant, Kb to CH3NH2 You should get one of the following answers O 4,91 105 O 2, 14 1011 O 6, 61 103 O 1,51 1012 O 4, 67 104

The dissolution of ammonium nitrate is given by the reaction NH,NO,(s) NH (ag) NO, (ag) Part 1 Assuming that the values of AH and AS do not change appreciably with temperature, calculate the AG value for the reaction from the polyatomic ion data in standard thermodynamic property tables. AG kJ Part 2 Predict the lowest temperature at which the

A 25.00-mL sample of a commercial bleach is diluted to 1 L. A 25-mL aliquot of the diluted sample is transferred by pipet into a flask that contains an excess of KI, reducing the OCl to Cl and producing I3-. The I3- content is determined by titrating with 0.09892 M Na2S2O3, requiring 8.96 mL to reach the starch indicator endpoint. Report the %w/v

Complete the following table.

Number of Molecule valence electrons Formal Charge ElectronGroup Geometry Molecular Geometry Resonance Sicij 54 Si Trigonal Planar S Select one . Select one GeH,CI Ge Trigonal Planar Ge GeSelect one Select one SnHAt, Sn 2 Sn Select one Sn Select one Select one sieri, 4 S Select one Select one Select one St Sr SrSelect one SrSelect one . Select one

Analyse the plot below that shows absorbance at 405 nm as time (s) increases. Select the absorbance values that best match the data points shown. Absorbance (405 nm) 1 0.8 0.6 0.4 0.2 0 Absorbance at 405 nm as time (s) increases 50 100 Time (s) 150 200,0 0 50 100 Time (s) 150 O 0.00, 0.325, 0.981, 0.243, 0.421, 0.112, 0.920 O 0.00 nm, 0.317 nm,

What is the approximate initial velocity (Vo) of the enzyme catalysed reaction shown in the graph below Rate of enzyme catalysed reaction 0.9 y 0.4058x 0.0268 R 0.9925 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.5 1.5 2.5 Time (min) O 0.406 mMmin O0.406 absmin O 0.406 VmaxKm O0.993 absmin O 0.406 abss Absorbance (405 nm)

A competitive inhibitor is a molecule that is able to bind to the v site of an enzyme, thus v the reaction that is catalyzed by this enzyme.