Chemistry Questions and Answers April 23, 2020

9. Consider a salt solution of unknown concentration. 1. In the laboratory you weigh an empty vial and determine the mass to be 14.096 g. You then measure out exactly 9.95 ml of the salt solution and add it to the premised vial. You then weigh the vial again, with the salt solution in the vial and determine the mass to be 24.547 g. Calculate the

Propose a structure for the compound that has the following spectra NMR 81.28 (3H, t, J 7 Hz) 8 3.91 (2H, q, J 7 Hz) 85.0 (1H. d. J4 Hz) 86.49 (1H. d. J 4 Hz) ppm IR 3100, 1644 (strong), 1104, 1166, 694 cm (strong) 1 no IR absorptions in the i range 7001100 cm or above 3100 cm Mass spectrum m2 152, 150 (equal intensity double molecular ion)

Your agarose gel electophoresis results from the double digest of six clones you screened for the incorporation of insert are as below. (M Marker (base pairs) Clone 16 U uncut C cut(digested)) MUCUC UCUCUCUC 000 2000 1000 The vector used has a backbone of 2941 base pairs and the desired insert is 1240 bases in length. Which of the clones

A method for the analysis of Sr2 suffers from an interference when Ba2 is present. When the concentration of Sr2 is 50 times greater than that of Ba2, the analysis of Sr2 gives a relative error of 2.04 . What is the value of the selectivity coefficient (Ksr.Ba) for this method Answer to 2 decimal places, no units.

Inorganic phosphate inhibits the phosphatase activity, less pNP are formed when high conc. of inorganic phosphate are added. How phosphate inhibits the production of pNP and which stages of phosphatase reaction occurs.

1. What is the identity of Elements 1 and 2 in the green rock 2. In the graphs below, sketch the mas spectrum for cach element write the symbol of the isotope above each spectral line. Mass (a.m.u.) Mass (am.u) 3. Although nickel has a higher atomic number than cobalt, nickels atomic mass is les than that of cobalt. Why 4. (Opeienal Is thin ruck a

The mass of the Empty Flask is 49.6536gand the Density is assumed to be 1.

Ill fipet Tlalibiration. True Volume Appeck ent alPpRalent Mass of mos5 of pipet scadig (m1) 0,00 1000 Plask (5) 4A 6536 SO.6535 5.6468 52. 6389 53. 35 54.6315 55,6285 1000 1000 Wood T24 C

4. Working with the same equation plot the concentration of vacancies in the same temperature range for activation energies of 1, 2, 5, 10, and 100 eV. Plot all these on the same plot and make each color distinct (have fun and make it look fancy). Also show this as a LogLog Plot ,I, A exp (2) where r, is the number of vacancies, A is a fitting

Calculate the energy released when 1000 hl of wort of density 1060 kg m-3 are fermented to 1000 kg m-3. What is the maximum rate of energy release if the maximum attenuation is 5 kg m-3 density units h-1. Note a solution of 1060 kg m-3 (60 kg greater than the density of water due to the dissolved sugars) is approximately equivalent to a 15% w/w

2.17 A very simple model of a polyene is the free electron molecular orbital (FEMO) model. Regard a chain of N conjugated carbon atoms, bond length Rcc, as forming a box of length L (N 1)Rcc. Find an expression for the allowed energies. Suppose that the electrons enter the states in pairs so that the lowest N states are occupied. Estimate the

A major component of gasoline is octane (c8h18). When liquid octane is burned in air it reacts with oxygen (o2) gas to produce carbon dioxide gas and water vapor. Calculate the moles of oxygen needed to produce .085 mol of carbon dioxide. Be sure your answer has a unit symbol, if necessary, and round it 2 sig figs.

Based on what we have learnt, please work out a way of synthesizing (a) PS bPMMA block copolymer with controlled molecular weight at each block, and (b) PSrPMMA random copolymer.

The density of aluminum is 2.70gmL A small piece of aluminum foil measures 8.13 cm x 4.83cm and has a mass equal to 0.5311g. Calculate the thickness of the sheet to the correct number of significant figures.

A boy wants to mix up 500 grams of cake batter for his self-made chocolate cake. 100 Watts of mechanical energy is produced by the mixer and is transferred into heating up the cake batter. The cake batter has an average heat capacity of 2800J/kg.C and has a temperature of 7C, before mixing. We assume thatLa reacc the cup with batter is insulated

All amino acids have two ionizable functional groups an aamino group (average pKa of 9.4) and an acarboxylic acid group (average pK, of 2.2). Tyrosine also has an ionizable side chain (R group) with a pK of about 10.1. One of the possible ionization states of tyrosine is shown. H3NCH COH CH2 OH At what pH would the structure be the predominant

A closed, cylindrical vessel is completely filled with water. The water is perfectly stirred. The volume of the stirrer may be neglected. The power delivered by the stirrer to the water may also be neglected. Initially, the temperature of the water is 100C. The water loses heat to the surroundings. The temperature of the surroundings is Ts=20C.

An air flow circulates inside a cylindrical tube that enters at 27 C and leaves at 327 C, receiving a constant flux density from the wall. By admitting laminar and stationary regime, simplify the energy variation equation.

3. A flow of nitrogen circulates inside a capillary cylindrical tube caused by a pressure difference of 90 atm between its ends. Nitrogen enters the tube at the same temperature as the outside air. The tube is exposed to outside air so the nitrogen will exchange heat with the air. Allowing for steady state, simplify the equations of variation.

The method of standard additions was used to determine nitrite in a soil sample. A 1.00mL portion of the sample was mixed with 20.00 mL of a colorimetric reagent, and the nitrite was converted to a colored product that produced a blankcorrected absorbance of 0.350. To 59.00 mL of the original sample, 1.00 mL of a standard solution of 1.00x103 M

The data in the table below were obtained during a colorimetric determination of glucose in blood serum. Glucose concentration, mM Absorbance, A 0.0 0.002 2.0 0.150 4.0 0.294 6.0 0.434 8.0 0.570 10.0 0.704 (Use a spreadsheet to complete this question.) Assuming a linear relationship between the variables, find the leastsquares estimates of the

Chemical Equations Instructions Write the word equations for the chemical equations below and determine the type of reaction (synthesiscombination, decomposition, singledisplacemet, doubledisplacement, or combustion). 1. 2 0 2 , 2 2 Water molecules decompose to equal four hydrogen atoms and two oxygen atoms decomposition reaction. 2. CHAG) 2 02

(4pts) Calculate the moles of Cl in the product (5pts) Enter the empirical formula for your product. BIIIU EI EIE NTI E IT Normal

Phenol OH groups have an approximate pka of 10, while NaHCO3 (the conjugate acid of Na2CO3) has a pka of 10.3. This means the phenol and its conjugate base (phenoxide) should exist in equilibrium (11) in the basic solution however, phenoxide is the major product of this reaction. What might account for this shift in equilibrium

Sample fatty acidglyceroll (2B) fatty acidglycerol (3B) Vegetable oil 0.01105 0.01052 lard 0.01115 0.01335 b. (5 points) Do these numbers validate your expectations for a pure triglyceride mixture Why or why not

I 3 + [11/ I | 11 ] + TASK: 1. draw a MO-Diagram for I 2. What is the bonding order? 3. what point symmetry do I 3 + has? 4. draw the MO'S

9) How do you expect the cysteine thiol will be affected by hydrogen bonding to the side chain of a glutamic acid in the dipeptide structure shown A) It will decrease the pka of the thiol B) It will increase the negative charge surrounding the sulfur atom C) It will increase the Ka of the thiol D) It will make the thiol more reactive as a

Test Yourself Find a,,2 if free, unprotonated NH, 0.02 M. 3D

(2) H30 OH PC 10 Ho. CH2C2 12) NABH4 SOCIe 12. 13. O LAH O 12.

Complete the followng the machanima. 1. HBr OH 2. M Br

prew the produet lor the folowing reactlons (2)MyC, Hz0 2. Na By NaoH ONA ABr END

PAGE 647g sample of a compound known to contain only A on, hydrogen, and oxygen was burned in oxygen to yield 8. 8635 g of Cos and 0.1767 g of Hao. formula of the compound What is the empirical a) CHO b) CaH20 c) C3H302 d) CeHOOH e) CaHeO2 The electron configuration of an element in its ground state is illustrated above. Which, if any, of the

2. Identify 2 functional groups in each molecule below. NH2 HO H3C HO, H2 HO, CI

A sample of an unknown radioactive nuclide initially contains 20x1010 atoms. After 16 days, 5x1010 atoms remain. What is the halflife of the nuclide

A compressor must transport lowpressure saturated steam from a boiler at 4 bar to the top of a steamstripping column at a water purification facility. The steam transportation pipes in this system are all 2.5 internal diameter. The column feed requirement is 15 mmin steam at 1 bar and 150 C. The compressor is located 3 ft above the boiler and the

Synthesis 3. (32 pts) Do all three below. Turn your work in on separate sheets. DONT work on this page. Dont show mechanisms here. Show your work on separate sheets, in order. Make each compound below using only the indicated carbon sources. You may use any other reagents, solvents, or organic compounds required as long as they dont contribute

Divalent carbon species called carbenes are capable of fleeting existence. For example, methylene, :CH2, is the simplest carbene. The two unshared electrons in methylene can be either paired in a single orbital or unpaired in different orbitals. a. Identify the type of hybridization you expect carbon to adopt in singlet (spin-paired) methylene and

3) The pKa of barbituric acid is 4.01 the sodium salt of barbituric acid has a small Ksp. At what pH do we find the maximum solubility of barbituric acid Why is it not useful to use extreme values of pH with this compound when you are trying to make it soluble

2. (15 points) Consider the oligopeptide given below (written in the 3 letter code) GluHisTrpSerGlyLeuArgAlaGly Answer Parts A D below Part A Draw its full chemical structure as it would exist at pH 8, then answer the questions below. You do not need to indicate stereochemistry, but make sure it is correct if you do. Part B Identify the net

Sara has calculated her tax due to be $4900. She has a 12% marginal tax rate and 11.35% average tax rate. But she found out that she is also entitled to a $1500 American opportunity tax credit and already paid $5200 in withholding through her employer. How much will her refund be? a. $1800 b $470 c $300 d $480

1.4. Duponts Kevlar is a highstrength, highmodulus fiber. The chemical repeat is shown as below (Allen Q2. 11.) Bond lengths cC 1.54 H cC1.33 NC1.47 (a) Assuming Kevlar to be a rigid rod, estimate the endtoend distance of a polymer with a molecular weight of 140,000 gmol. (For simplicity, bond angles of NH and CO within repeating unit can be

For the following reaction looking for: 1)a complete mechanism for the reagents/substrates and product, as well as a detailed mechanism for the catalyst including the TPGS-750-M and KHSO4. 2) Name of product and substrates, reagents, catalysts and products. thank you

1 (2.5 mol ) 2 wt TPGS750M KHSO, (0.02 M), rt

Opgave 2 Sekvens A MeOH HCI FmocCl OH H,N aq. Na,cO, H CH,CI, dioxan 1) aq. Na,CO,CH,CN 2) HCI til pH 3 3D

5+4(-3)+2+00

ions of arsenic are present in 1 mL of that 10C, low potency, dilution of pure arsenic trioxide?10^-23 (ions/mL) concentration of a 30C, standard potency, arsenicum album remedy: 10^-60 ion/ltr ions of arsenic are present in 1 mL of that 30C, standard potency, arsenicum album remedy : 10^-63 Ion/mL 1. Obviously one cannot have a fraction of an

Complete the calculations

Trial 1 Trial 2 99.612 79.023 Mass of Water 3.702 52.230 Mass of NaOH(s) 103.314 g 131.253 g Total Mass in Cup 1.311 mol 0.0928 mol Moles of NaOH 20.2 22.0 Initial Temperature 30.0 33.3 Final Temperature Change in Temperature 9.8 11.3 Trial AH m,dissolution (1pts) Average AHAlsolation (kJmol) (1pts) Accepted AH mdissolution (kJmol)

Describe the interaction/binding of CO with a transition metal. Which factors are important for the binding strength of CO to a metal and how can this binding strength be quantified?

Rank the following molecules in order of increasing MCO binding strength and justify your ranking: [Ni(PPh3)(CO)3]; [Ni(PBu3)(CO)3]; [Ni{P(CF3)3}(CO)3]; [Ni(H)(CO)3]+; [Ni(PBu3)2(CO)2].

Hydroformylation of alkenes is usually carried out with rhodium catalysts. However, depending on the choice of ligand, the compound [Pd(PP)(OTf)2] is also a hydroformylation catalyst in the presence of small amounts of an organic acid (PP is a bidentate neutral ligand, OTf is a weakly coordinating anion). Give a likely mechanism for the

Depending on the ligands, palladium compounds are also good catalysts for hydrogenation and CO/alkene co-polymerization. Which byproducts can be formed in the reaction mentioned under (c)?

Adiponitrile (1,4-dicyanobutane) can be synthesized from butadiene and HCN using a homogeneous nickel catalyst. Adiponitrile is a precursor for Nylon-6,6. a) Propose a mechanistic cycle for the formation of the first hydrocyanation product from butadiene with the precursor catalyst [Ni(PP)2] (PP = bidentate phosphite ligand). Which two products

In the hydrocyanation of styrene (see figure), two products can be formed. Discuss the terms regioselectivity and enantioselectivity using these products. Give an example of how enantioselectivity of a reaction generally is reported, with its meaning. List the requirements for substrate/ligand/catalyst that are necessary to reach good

Gaseous butane (CH,(CH) CH, reacts with gaseous oxygen gas (o, to produce gaseous carbon dioxide (CO,) and gaseous water (H,O), what is the theoretical yield of carbon dioxide formed from the reaction of 54.6 g of butane and 80.2 g of oxygen gas Round your answer to 3 significant figures.

Which signal from the H NMR of this compound is expected to be the furthest downfield H the methyl protons signal O the methine protons signal O the methylene protons signal O the aldehyde proton signal ,This is the infrared spectrum for the compound (00 4000 1000 RVEM Part AWhat functional group(s) are indicated in the infrared spectrum1 INSERT

2. (10 pts total) The World Health Organization uses rehydration therapy for cholera patients. The therapy uses an aqueous solution containing 3.50 g NaClL, 2.50 g NaHCo.L, 1.50 g KCIL and 20.0 g glucoseL. Remember the chemical formula for glucose is CH,Og. a. (5 pts) Calculate the osmolarity of this solution. Remember osmolarity is Z(ic)n b. (3

3.39 Tin (Sn) exists in Earths crust as SnO 2.Calculate silicate, CaSiO 3. This compound can absorb up to 2.5 the percent composition by mass of Sn and O in times its mass of water and still remains a freefl owing SnO 2.

2 In water, ratie of exygen to hydrogen by atoms is A21 B 12 C81 D 18 3 Isotopes are atoms of the same element with different numbers of A Protons B Electrons C Neutrons D Positron 4 Which of the following places the atomic subshells in the correct order of relative energy, starting with the subshell of lowest energy Ad. p.s Bs, d, p Csp.d Dp,s, d

What is the importance of the Samwers brothers? What would happen if they left or sold Rocket Internet? (300 words)

Draw the compound given the HNMR, CNMR, mass spectrum, and IR spectrum. M+* peak is at 108 m/z

The infrared spectrum, 13C NMR spectrum, H NMR spectrum, and mass spectrum data for a compound are given in this question. This is the infrared spectrum for the compound LOD D 4000 3000 2000 1500 1000 500 HAVENUMBERI l TRANSMITTANCEII

Tim is measuring the concentrations of neurotransmitters produced by rat brains when fed with an alkaloid stimulant. His replicate results yielded the following concentrations (in M): 116.0, 97.9, 114.2, 106.8 and 103.3. For four degrees of freedom, students t at 90% CI is 2.132. a) 10 pt. His standard control solution is guaranteed to yield 116.2

What is the working principle of the Beer-Lambert Law?

What is and what is the operation of a spectrophotometer? What is it for?

How does the Biuret reagent work? What is its use and what is it used for?

The following set of data was obtained when creating a calibration curve for the gas chr (GCMS) based analysis of the anabolic steroid metabolite 19norandrosterone in urine Concentration of 19Norandrosterone (ngnt) Peak Area of 19Morandrosterone Peak Area of 19 0.5 50 100 200 400 300 labelled 19Norandrosteroned3 is the internal standard) a Sketch

Electron Pair Molecular Molecule Lewis Dot Structure Arrangement Geometry Polarity H2S HSH CH,CI HE O3 O st SiO2 3. Both Cs Both Cs C2H2 HCCH Actual SO drawn as octet 38 NF3 CH20 H2H CC4 CHCHCH2 CEP FCP C CHNH2 N N CH3OH 0 Both es Both Cs C2F4 CH3COOH H

I need help with magnetic moments for inorganic chemistry. I am trying to make sense of my lab I performed on magnetic moments on metal ions in substances. I determined the number of unpaired electrons. What does this tell me about its stereochemistry? Or am I supposed to be looking at a different value to compare the stereochemistry? I have

In this experiment, it will study the reaction between crystal violet and sodium hydroxide. One objective is to study the relationship between concentration of crystal violet and the time elapsed during the reaction. The equation for the reaction is shown here. NICH32 NICH3)2 OH (ON(CH)2 OH N(CH3)2 N(CH)2 N(CH3)2 A simplified (and less

Datasheet Color Red Yellow Green Blue Unknown 1 Unknown 2 15 d Re FDC Name,Each food color is made up of two FDC dyes. The dyes included in the food coloring may include erythrosine (FDC Red 3) , Allura Red AC (FDC Red 40), tartrazine (FDC Yellow 5), andor Brilliant Blue FCF (FDC Blue 1). They comprise the food colorings as follows Color Red

3. Weigh four samples, each containing enough Na2CO3 to react with 25 mL of 0.1 M HCl and place each in a 125mL flask. When you are ready to titrate each one, dissolve it in 25 mL of distilled water. Add 3 drops of bromocresol green indicator and titrate one rapidly to a green color to find the approximate end point. 2HCI Na2CO3 CO2 2NACI H20

GZEXP. 6 HCI Procedural Step 3 Please explain how a final calculated HCl molarity could be affected il they recorded the mass of sodium carbonate at the analytical balance but then accidentally spilled some of the sodium carbonate when they transferred it to their Erlenmeyer flask (would the HC) be higher, lower, or no change) Please explain with

What is the atomic mass

Solve it . Draw the three dimensional structure of ONE Meso stereoisomer of 2,3 dibromohexane and assign R and S configurations to the centers of chirality. Draw the structure of a diastereomer of this Meso compound.

WF VQ D N N G KK QE IL Absolutely conserved Conserved by type Not conserved ,If an amino acid is found at the exact same location in the alignment of two homologous proteins, that amino acid is said to be absolutely conserved. An amino acid type can also be conserved at a given position. Using the BLAST sequence alignment above, sort aligned

Give the first step of the reaction between the following pentapeptide and the reagent Use curly arrows to show how the bond between the reagent and the relevant amino acid residue is formed there is no need to show the cleavage of the amino acid from the peptide. 7. supplied. ala.phe.asp.met.gly NCS with 8. Starting from the Merrifield resin

Draw the resonance hybrid for the following compound. HN 0

The chemical 1,4 dichlorobenzene (1,4 DCB) is sometimes used as a disinfectant in public lavatories, and has strong fragrance potential. At 20C (68F) the vapor pressure (P), a measure of the gas phase concentration for 1,4-DCB, is 5.3 x 10-3 atm. Gas phase 1,4-DCB concentration is also expressed as 3.2 g/m3. (A) Estimate the Molecular Weight of

metathesis reaction of 1-hexene with benzyl acrylate in an aqueous solution of TPGS-750-M + KHSO4

1 (2.5 mol ) 2 wt TPGS750M KHSO, (0.02 M), rt

3.) On the next page is the result of a Beers Law plot obtained in the lab. As can be seen, the Yintercept is below zero, when Beers Law indicates that it should be 0. Upon investigation, it was determined that the student used a common test tube instead of a cuvette to calibrate the spectrophotometer. He then used a cuvette for measuring his

3.) On the next page is the result of a Beers Law plot obtained in the lab. As can be seen, the Yintercept is below zero, when Beers Law indicates that it should be 0. Upon investigation, it was determined that the student used a common test tube instead of a cuvette to calibrate the spectrophotometer. He then used a cuvette for measuring his

Membrane maximal conductance2.0105Scm2 Area6.2832104 cm2 Total membrane capacitance Cm1.48841010 Farads Reversal potential for leak channel, Em 0.07 V init Vm(0) 0.07 V 1. write the first order equation in the standard form to describe this model and use mathematics to describe the system you are building, including de fining input, output and

Question 2 a, 1251 K, determine u, using units of cmVs. Assume To273 K, and determine u at 22 C. Lets say that a metal atom with atomic density of 1022 cm contributes an e per atom. Using po 22.8 n2m

From the water sample analysis: 40 mg/L Ca+2, 5 mg/L Mg+2, 10 mg/L K+, 10 mg/L SO4-2, and alkalinity which is equal to 122 mg/L as CaCO3. Calculate the TH, CH, and NCH. Also check the classification of water hardness of the water sample.

Consider the energy level diagram below 4C 2He 2O2e h k a Relative Energy Level AH ,Assign the following items to letters in the enthalpy energy diagram above The figure is not drawn to scale. 3 AH fifumaric) AH Tmaleic 3 maleic acid maleic (s) fumarice AH sifumaric) AH s(maleic) 3 AH citumaric 3 AH cmaleic) 4CO 2H,O) fumaric (s) 3 3. 3. 3. 3.

THE COMPELETE ENERGY DIAGRAM (You can type the letters in the yellow box below the table ) Consider the energy level diagram below 4C) 2H29 2O2e) d. i f h k a heet1 Relative Energy Level AH ,Assign the following items to letters in the enthalpy energy diagram above The figure is not drawn to scale. AH itumaric) AH fmaleic) 3. maleic acid (e) 3.

Chemistry Mass of lauric acid is 5.103g

Determining the f.p of a solution of lauric acid with an unknown Mass of unknown lauric acid apparatus 22.9483 g Mass of unknown 0.8343g Data recorded every 1min for the solution Time (min) Temperature (C) 50 2. 49 48 4 47 46 6. 44 7 42 40 38.5 10 38.5 11 38 12 37.8 13 37.8 14 37.7 15 37.7 Graph the data in the table as above in Part A. and

An aqueous solution of copper(II) acetate has a concentration of 3.99 10 -2 molal. The percent by mass of copper(II) acetate in the solution is %.

(b) (5 pts) Draw the conjugate base for each of the acids shown HO, CH3 (i) NH2 OH (ii) CH3 H3C CH3 (ii) (iv) CH3NH3 SeH

Based on your knowledge of the famous Hodgkin & Huxley experiments and the basic ionic foundation of the action potential, graph the current-voltage relationship for K + in squid giant axon. Be sure to label the axes and any other relevant aspects of the graph.

.) CH 4 CH3CO,H Products (Starting Reagents) (Target Molecules) Me Me , CH3CH3,CH4 Products (Target Molecules) (Starting Reagents)

Please help Complete the synthesis by showing how to prepare the target molecules using any known reactions, inorganic reagents, and known/given starting materials.

.) CH 4, CHCO,H Products (Starting Reagents) (Target Molecules) Me Me , CH3CH3,CH4 Products (Target Molecules) (Starting Reagents)

4.(20 pts) An accident releases 30 of the inventory of the I133 and Kr87 from a 4,500 MW th reactor into a containment building that leaks at 0.2 per day. Calculate for a point 500 m from the plant and under Pasquill F, 1.5msec conditions (a) the 2hr external dose (b) the 2hr thyroid dose.

Consider the reaction below Br2 (g) 2Br (g) K 1.04 x 103 An 0.5 L vessel containing an equilibrium mixture of the gases contains 0.3 g of Br2 (g). What is the mass of Br (g) in the vessel O 0.097 0.045 none are correct O 0.079

What is the iupac name this compound

HO

Which one has the highest frequency Carbonyle Stretching bands (A) Ni(CO)3(PH3) (B) Ni(CO)3(PCl3) (C) Ni(CO)3(PF3) (D) Ni(CO)3(PMe3)?