Chemistry Questions and Answers July 09, 2020

Consider a saturated solution of the salt MX3, which M is a metal cation with a 3+ charge and X is an anion with a 1 charge, in water at 298 K. Which of the following will affect the K sp of MX3 in water? diluting the solution the addition of more X to the solution raising the temperature of the solution the addition of more M3+ to the solution

A gas mixture comprising of two hypothetical gases, 2.82 moles of E and 4.89 moles of F, in a 12.5L container at 298K. What is the mole fraction of E 0.336 0.366 mol 0.577 0.577 mol,In a flask containing multiple gases (A, B and C), when the pressure is measured, this pressure reflects the TOTAL pressure (from all components) in the flask. Ptotal

The graph shown below depicts the relationship between concentration and time for the following chemical reaction InA This information indicates that the reaction is first order in A. the reaction is second order in A. A B the reaction is zero order in A. the reaction is first order in A and second order in B. the reaction is zero order in A and

Slaters Rule 0.35 d and f electrons 1.00 1.00 s and p electrons 0.35 0.85 1.00 1.00 1.00 n3 n2 n1 n What is the shielding constant experienced by a 2pelectron in the nitrogen atom Then calculate Zetor 2p electron. Nitrogen has total 7 electrons. Please show all the calculations and reasoning

You have a 10.24 cm3 of a weak base with pKb = 4.1024. Its concentration is 0.2 mol/dm3. You are titrating with 0.1 mol/dm3 HCl. (a) How much acid must you add to reach the equivalence point? (b) Before any acid is added, what is the pH of the weak base solution? (c) At the equivalence point, what is the pH of the solution? (d) At the

A 3.54gram sample of a certain diatomic gas occupies a volume of 3.30L at 1.00 atm and a temperature of 45C. Identify this gas. A) N B) 0 C) F2 D) H E) Cl

Consider this phase diagram for carbon. Which phases are present at the upper triple point graphite gas liquid diamond Which phase is stable at 1 atm and 273 K liquid gas diamond graphite (atm) 106 105. P 103 lower the pressure lower the temperature and raise the pressure raise the temperature and raise the pressure raise the temperature and lower

For a reaction, AG, 240 kJmol. What is the equilibrium constant for the reaction at 58.1C Select one a. 1.92e58 b. 5.21e59 c. 1.14 d. 0.608 e. 1.66e216

When I computed 1.5/5.9x10^-4 I got 2.542 but the person who helped me earlier got 2542? When I calculated the sq.root of (5.9x10^-4x1.5), I got 2.9748 but the person who helped me got 0.0297? when I compute 1.0x10^-14/2.0x10^-10, I get 5E-25 not 5.0x10^-5 If someone has a TI-84 silver and can tell me what I can do to get the right answers? This

Which method(s) below can be used to produce a formate (HCOO) buffer with a pH of 3.00 The K, for formic acid (HCOOH) is 2 x 104 at 25C. (You do not need a calculator to answer this question). I. mix equal volumes of 0.50 M HCOONa and 0.50 M HCOOH II. mix a calculated lesser volume of 0.50 M HCOONa with a calculated greater volume of 0.50 M HCOOH

Questions 1 2 refer to the solubility of iron(II) phosphate, Fe3(PO4)2 Fe3(PO4)2(s) 3Fe (aq) 2PO4 (aq) 1. The Ksp for Fe3(PO4)2(s) is 1.0 x 1036 at 25 C. What is the solubility of Fe3(PO4)2 in mol L a) 2.5 108 b) 3.1 x 108 c) 6.3 108 d) 1.0 x 107 e) 4.0 x 107 2. If 25.0 mL of 2.0 x 105 M FeSO4 is added to 25.0 mL of a solution of 1.0 x 1010 M

Write the reactants (if applicable) and product(s) of the following reactions (15 points 3 points each) N(CH313 Ag20 A (heat) b. Ethanoic acid in the presence of 1. LIAIH,, ether 2. HCI HO c. Methyl acetate in the presence of 1. LIAIH,, ether 2. HCI HO d. Ethylene oxide in the presence of 1. LIAIH,, ether 2. HCI HO and. 1bromobutane 1.

Calculate the molarity of a solution prepared by dissolving 4.00 g NaOH into 100.0 mL of water. a little more than 4.00 M O 4.00 M O a little less than 1.00 M a little less than 4.00 M O 1.00 M O a little more than 1.00 M

Three forces act on a 1 kg object shown in Figure 3. As a result, it accelerates at 10.0 ms in the direction shown. The magnitudes of of F2 and F3 are 5 N and 8 N, respectively. Determine the magnitude of F. Explain your reasoning carefully. F 3 F 1.00 kg Figure 3 a 10,0 ms F

Which factor influences the value of the equilibrium constant for a reversible reaction A) removing reactant B) addition of a catalyst C) removing product D) raising the temperature. E) all of these

Muriatic acid is between 20-32% hydrochloric acid. A particular batch is determined to have a concentration of 11.26 M HCl. What is the concentration of HCl in a pool when 2.0 L of 11.26 M HCl are added to a pool with a total volume of 4500 L?

Calculate the molarity of a solution prepared by dissolving 4.00 g NaOH into 100.0 mL of water. a little more than 4.00 M O 4.00 M a little less than 1.00 M a little less than 4.00 M O 1.00 M a little more than 1.00 M

What is the predominant intermolecular force in CH3NHCH3 dipoledipole forces O Hydrogen bonding O London dispersion forces Olondipole ineractions O lonic bonding

(i) Define a buffer and explain how buffers work (ii) Give examples of indicators and how they work, Construct a galvanic cell for the reaction Zn Cu Zn Cu. Identify the anode and the cathode. And hence construct the cell. Deduce the cell notation.

(Modified from Chemistry A Molecular Approach, 1 Ed. by Tro) Consider a solution that is 0.020 M in Cu and 0.015 M in Fe. D (a) If sodium hydroxide is used to selectively precipitate one of the cations while leaving the other cation in solution, which cation will precipitate first What is the minimum concentration of NaOH that will cause

1. Write the net ionic equation for the following 2. When setting up their experiment a student discovered that the solution in their flask turned a bright pink upon adding two drops of the indicator even before beginning the titration. What do you suspect was the mistake that the student made?

KHC HO (aq) NaOH(aq) KNaC HO (aq) HO(1)

For reaction, A B 10L volumetric flask at 25C. If K 0.238 are available C D Given that initial amounts of 0.68 mol of both A and B in a at equilibrium, how many moles of each reactant and product

The diagram below shows two setups, X and Y, with different amount of water in each beaker. The beakers were placed above two Bunsen burners for 5 minutes. beaker X 100 ml of water 70 60 50 40 Setup X 0 The temperature of the water in the two beakers were recorded as shown in the graph below. Temperature (C) plastic covers Bunsen burners Setup X

Use standard enthalpies of formation to calculate AH for each reaction. a. b. C. d. rxn 2 HS(g) 3 O(g) 2 HO(1) 2 SO2 (g) SO(g) 2O2(g) SO3 (9) C(s) HO(g) CO(g) H (9) NO4 (9) 4 H(g) N(g) 4HO(g)

Balance the following reaction using the ionelectron method for reactions happening in acidic solution. NH4 CIO NO Cl Fill in the blanks. Enter a single number for each coefficient. Enter0 if that substance has cancelled out. HO 1 NH4 2 0 2 H O HO 0 H CIO 2 NO 1 Cl

Select the best description of this structure in terms of possible geometric isomers. st Select one O Compound without geometric isomers O E isomer (priority groups on the opposite side) O Z isomer (priority groups on the same side) O Z isomer (priority groups on the opposite side) O E isomer (priority groups on the same side)

For a reaction, A 3B Given that 0.5 mol of A are mixed with 1.5mlo of B in a 2L volumetric flask. At equilibrium the number of mol of C was found to be 0.221. For each reactant and product, calculate the concn at equilibrium and hence calculate the equilibrium concentration. C D

2. A uniformly charged thin spherical shell of radius 3cm produces an electric field of 2 NC at a radius of 6cm from the center of the sphere. Find the electric flux 10 cm away from the center of the sphere. Draw diagram and show all necessary solutions. (10 marks)

A 0.800 g sample of impure potassium chloride (KCI) was dissolved in deionised water and was treated with a silver nitrate (AgNO3) solution in excess to give 1.460 g of silver chloride (AgCl) precipitates. Calculate the percentage of potassium chloride in the sample.,An impure sample of Na3PO, weighing 0.1392 g is dissolved in 25 mL of water. A

Which do you think would have a higher surface tension liquid neon or liquid krypton?

What is the enthalpy of reaction for the following reaction 2HO(g) 2H(g) O(g) Bond HH O0 HO Bond energy (kJmol) 436 499 460

The balanced equation for the dissolving of magnesium nitrate in water is Mg(NO),(s) Mg(aq) 2NO, (aq) (a) How many Mg (aq) and NO3(aq) ions form for each Mg(NO), formula unit that dissolves (b) How many moles of Mg2 and NO form for each mole of Mg(NO), that dissolves HO

Provide a structure of product A in the reaction given below and outlin mechanism for the formation of this product. 1. NaOEt 2. 3. H3O PRODUCT A

Determine the product of the following synthesis. 1. KCN 2. MgBr 3. HO

How many grams of Mg(OH)2 form when 75.0 mL of 0.60 M NaOH react with excess magnesium chloride MgCl 2NaOH 2NaCl Mg(OH)2 g Mg(OH)2 Mass Mg(OH), (g) Enter

Draw, complete and EXPLAIN the mechanism of the reaction of ethyl propyl ketone with methanol in a medium containing an excess of hydrochloric acid. (20 points):

All of the following are expected to have a value of zero for the enthalpy of formation, except:

O (g) C (s) as graphite 12 (9) Fe (s)

Place in ascending order (from smallest to largest) according to their pKa and explain your answer (6 points) H3C . CH3 by CH3 br H3C 0 IQ

For a reaction Rate kAB2, what factor will NOT change k A) adding catalyst B) adding inhibitor C) raising temperature D) increasing A E) none of these

Assign R or S configurations to each of the stereogenic centers in the following molecules. For each molecule you must show your reasoning. Given Atomic numbers H1, C 6, O 8, N7, Cl 17 i. (iii) CI H3C HO .... CHCHCH3 OH I CH,NH, ii. HO C (iv) H3C Ol.. CN

The stepwise formation constants for the replacement of four aqua ligands in Cu(HO)61 by ammine ligands are log K 4.0 log K 3.2 log K3 2.7 and log K4 2.0. What is the value of 34 for this reaction O 69 O 1.19 x 104 O 7.9 x 1011 11.9 6.9 x 108

For the following reactions, predict what the product would be:

H3C H3C H 1. Hg(OAc)2, CH3OH 2. NaBH4

Q1. The vibrational frequency of the HCI is 2.988 x 105 cm.. Calculate the zero point energy of molecule (in joules) Q2. Calculate number of vibrational modes, stretching vibrations and bending vibrations for the following molecules C6H6 NN0 CH2O CH,C1 N

Structures of compounds A and B show hypervalent sulfur in NSF and NSF3. Draw resonance structures for each molecule that retains an octet of electron around the S atom. NS A F SIF B

The decomposition of AB (g) to A(g) and B(g) is first order with respect to AB. If the rate constant for 1 the reaction is 0.530 hr answer each of the questions below. a) What is the rate of decomposition when AB (g) 0.290 M Rate b) What is the halflife of the reaction (in hours) t12 2 Ptot Mhr hr c) If the initial pressure of AB (g) in the

Calculate the lower and upper heating values of the following fuels, during combustion with air. H2, CH4, and CH3OH at 298.15 K and 1 atm. For methanol, use the following reaction formula: CH3OH+3/2O2--->CO2+2H2O

Brachytherapy is a type of radiation therapy that is used to treat cancer. It involves temporarily placing a small seed made of a radioactive source inside the patient to kill cancer cells and shrink tumors.

The heat capacity, CP, of 1.500 moles of F2 is 46.95 J.K1 at 25C. Assuming the gas is ideal, calculate the molar heat capacity, w, Deltau, q, and at constant volume, CV, m for F2 at 25C.

Which of the following compounds represent meso compounds compound you must show your reasoning. Bri A Br CI B CI 2 OH OH C For each

Predict the rate law for the reaction 2 BrO(g) Br(g) O(g) if a. The rate doubles when BrO doubles. b. The rate quadruples when BrO doubles. c. The rate is halved when BrO is halved. d. The rate is unchanged when BrO is doubled.

Which statement correctly describes the energy changes that occur when bonds form and when bonds break? No energy required when bonds form or when bonds break Breaking bonds is endothermic, and forming bonds is exothermic Both are endothermic Both are exothermic Breaking bonds is exothermic, and forming bonds is endothermic

Use retrosynthesis by making two lisconnects to synthesise the following two compounds show reagents for transformations Compound a Compound b HO F3C O 01 OH

Consider the following reaction HO (1) H(g) O (g) AH 285.8 kJ mol Which of the following statements is correct The reaction flask would feel warm The reaction flask is exothermic 39.7 kJ of energy is given off when 2.5 grams of water reacts 571.6 kJ of energy is needed to produce one mole of hygdrgen

Write the formulas for the compound formed by the following pairs of atoms. Examples technetium(II) borate Tc3(BO3)2 or technetium (1) nitrate TCNO3. cesium borate

For each of the following rate laws, determine the order with respect to each reactant and the overall reaction order. a. Rate kAB b. Rate AB c. Rate kAB

Select the elements you would expect to have the smallest and greatest electron affinities. Element Ge Fe F Ne K Electron Affinity smallest greatest X

What is the enthalpy of reaction for the following reaction CH4(g) 4Cl2(g) CCl4(g) 4HCI(g) Bond Bond energy (kJmol) CH 413 CICI 243 CCI 339 HCI 432

Consider the titration of 50.0 mL of a 0.120 M of hydrazine (NH), a weak base with a K, value of 3.0 x 10 at room temperature. If we titrate the above solution of hydrazine with standardized 0.100 M HCl, determine the following (a) the pH after 20.0 mL of the acid has been added. (b) the pH at the equivalence point. (c) the volume of titrant (mL)

Hydrogen gas reduces NO to N in the following reaction 2 H(g) 2 NO(g) 2 HO(g) N(g) The initial reaction rates of four mixtures of H and NO were measured at 900C with the following results Experiment 2 3 4 Ho (M) 0.212 0.212 0.424 0.848 NO, (M) 0.136 0.272 0.544 0.544 Initial Rate (Ms) 0.0248 0.0991 0.793 1.59 Determine the rate law and the rate

Show how the approach of solid phase peptide synthesis would be used to produce the Lysinealanine dipeptide shown below. Your synthesis may utilize any monomeric amino acid starting materials containing any protecting groups that you feel are necessary. Also, protecting groups and reagents may be indicated using abbreviations we learned in class.

Given the two half reactions that are used to construct a galvanic cell, calculate the cell potentials Cd 2e Cd E 0.40V Ag e Ag E 0.80V

Serum containing Na + gave a signal of 6.00 m V in an atomic emission analysis. Then4.00 mL of 2.00 MN a Cl were added to96.0 mL of serum. This spiked serum gave a signal of 9.00mV. Find the original concentration of Na + in the serum.

The isentropic compressibility coefficient its define by av s1 (37) s ap aVT Cp Ks b) Demonstrate that KsKt c) In general. for any substance, in which compression will decrease the volume more by applying the same Ap with the temperature and entropy constant

Write an equation relating the rates of change in the concentrations of the products and reactants in each of the following reactions a. F(g) HO() HOF(g) HF(g) b. Si(s) 3 HCl(g) SiHC13(e) H(g) c. 4 NH3(g) 3 O2(g) 2 N2(g) 6 HO(g) I

(a) Explain why the reaction of SF4 with BF3 yields SF3, whereas the reaction with CsF gives CsSFs. (b) Suggest how SF4 might react with a carboxylic acid, RCOOH

Ksp for PbCrO4 2.8 x 1013 at 25 C. Which of the following statements about the concentration of the ions in PbCrO4 solutions is always true whatever its molarity Pb (aq)5.2 x 107 mol L1 and CrO4(aq) 5.2 x 107 mol L1 Pb (aq) 5.2 x 107 mol L1 and CrO4(aq)5.2 x 107 mol L1 Pb (aq) 2.8 x 1013 mol L1 and CrO4(aq) 2.8 x 1013 mol L1 Pb (aq)5.2 x 107

An environemtal aqeous samples has 515 gmL of Gallium (III) ion and 323 gmL of Mecury (II) ion, NaOH solution is slowly dropped into the sample. (a) Determine which metal ion would precipitate first Show your reasoning, including the calculations involved. Given that Ksp for Hg(OH)2 and Ga(OH)3 are 3.6x1028 and 7.28x1036 respectively. (b) Comment

Following reaction is studied over a range of temperatures. 2HI(g) H(g) 1(g) The experimental results obtained are tabulated below 633 T (K) 666 697 715 781 k (litmol sec) 1.7105 1.07104 5.01104 1.05103 1.51103 1. Determine the activation energy graphically. 2. Determine by what factor the rate increases when the temperature rises from 300 K to

You are a consultant in a chemical laboratory and are responsible to suggest suitable extraction techniques for different chemical analysis. Based on the info described in the below cases, i) Propose an extraction technique for the below two projects ii) Support your answer with three reasons. a) Determine several phthalates, some organic

ch Moving to the next question prevents changes to this answer. Question 14 5 points Save Answer When you need to removedelete an empty Layer from current drawing, which of following is the correct (and only) method to do such A. Erase B. Delete C. Layer cannot be removeddeleted once created D. Purge Moving to the next question prevents changes

1. 2. Which product is formed when propyne reacts with NaNH2 and then CH31 followed by H2 and Lindlars catalyst 1 2 3 4 Which sequence of reactions will allow for the 3. Which of the following will feature a following transformation delocalized lone pair Select all that apply. 1 2 a Cis and trans2butene 3 b Cis2pentene 4 C O Cis2butene 4. Which of

2. (a) For the neutralization reaction (i) HB OH B HO Calculate the value of the equilibrium constant for 99.99 conversion of HB into B at the equivalence point, assuming that the analyte content is 5.000 mmol and the total volume at the equivalence point is 100.00 mL. (6 marks) (ii) Would a larger value of the equilibrium constant be expected

Starting with propene show a multi step synthesis of 1,4 pentadiene. Show a multi step synthesis to make the following conversion.

An object of mass m is released from rest at height 3R above the ground and slides down the frictionless vertical track as shown. The corner is a frictionless quarter-circle track of radius R. At the end of the quarter-circle track, it enters a horizontal track at x = 0. The coefficient of kinetic friction along the horizontal section increases

Create a titration curve (on graph paper) for the reaction of 25.0 mL of 0.050 M Ti3 and 0.0195 M C6H402 (quinone). The solution is 1.0 M in HCIO4 throughout the titration. Given, E Ti0T 0.1 V and E CaH4O2CaH4(OH)2 0.699 V. Show ALL the calculation works of the following stages i. ii. iii. iv. 6 points for preequivalence including 0.00 mL 1

How many moles of hydrogen gas, H2, is needed to produce 6.2 moles of NH3?

1. 2. Aldol condensation between two molecules of 3methylcyclohexanone can lead to a mixture of several products (not counting double bond isomers). Draw as many products as you can from this condensation. Explain why it is sometimes helpful to scratch the inside surface of the container with a glass rod to induce crystallization.

Complete the following table for an ideal gas. a. 7.74 x 10 Pa 12.2 mL b. V n c. 455 torr d. 745 mm Hg 43.0 mL 11.2 L 0.421 mol T 0.401 mol 25C 223 K 4.4 x 102 mol 331C

The effect of channeling increases the enzyme reaction rate by preventing intermediates from defusing to the active site (true or false)?

In 1983, the market shares for soap were Procter & Gamble with 37.1%, Lever Bros. with 24%, Dial with 15%, Colgate Palmolive with 6.5%, and all other with 17.4%. By 1991, the market shares for soap were Lever Bros. with 31.5%, Procter & Gamble with 30.5%, Dial with 19% Colgate-Palmolive with 8%, and all others with 11%. 1. Suppose you are

Use the given steam table for superheated HO at 200 MPa chamber pressure to develop an interpolating polynomial to fit the data and find the corresponding entropy S for a specific volume V of 0.108 mkg using Lagranges method. V (mkg) 0.10377 0.11144 0.1254 0.1382 S (kJkg.K) 6.4147 6.5453 6.7664 6.8457

Titration of the 12 (253.81 gmol) produced from 0.2091 g of primary standard KIO3 (214.001 gmol) required 29.62 mL of sodium thiosulfate, Na2SO3 (158.11 gmol). 103 51 6H 312 3HO 12 2SO3 21S406 Based on the above reactions, calculate the molarity of the Na2SO3.

A structural member in the shape of an L is supported by a pin joint at A and a roller at B as shown in Figure 1. At point B the wall is inclined at 30. Using your knowledge of rigid bodies in equilibrium, determine the reactions at point A and B for the system in Figure 1. 300 mm 250 mm 330 N 250 mm B Figure 1 A structural member 30

D) The local average power delay profile in a particular environment is found to be P(t) n0 106(n 1) 8 (tn106) (i) Sketch the power Delay Profile of the channel in dBm (ii) What is the rms delay spread (o,) of the channel (iii) If the channel is to be used with a modulation that requires an equalizer whenever the symbol duration T is 100,,

Given the data in the table and the information below, please answer the following question. Show all working and formulas used. Maturity (T) Spot Rate () z(1) (2) z(3) (4) z(5) L(6) 0.15 0.22 0.25 0.28 0.20 0.13 Misty would like to invest 10,000. She is faced with the choice between 2 investments Option 1 invest for 5 years Option 2 invest for 3

3. Assign the H NMR spectrum of acetophenone CDCI3 below

(i) Assign all of the peaks listed for the H NMR spectrum. Give reasons for your assignments.

8. (5 pts each) For each transformation below, (a) Label the newly formed functional group in the product. (b) Provide reagents that will accomplish each of the transformations below.

Compare between light microscopes and electron microscope.

Choice of the method of chromatography depends on some parameters, note them.

Draw Lewis structures for the compounds represented by the following condensed structural formulas. a) ) CH 3 CH 2 C(CH 3 ) 2 CH 2 CH 3 b) (CH 3 ) 2 CHCH 2 OH c) ) CH 3 CH 2 C(CH 3 ) 2 CH 2 NHCH 3 d) CH 3 CH 2 C(CH 3 ) 2 CH 2 CN e) HCO 2 CH3

A concentration cell consists of two halfcells with identical electrodes but different ion concentrations. Consider the following concentration cell (pictured below). M(s) M(satd MX) M(0.100 M) M(s) Ecell 0.417 V At the anode, a metal electrode (M) is placed in a saturated aqueous solution containing ions of the same metal (M) and a halogen

Calculate the number of formula units in a 25.5 Kg sample of NISO4 a) 1.25x1026 formula units b) 9.92x1025 formula units c) 1.38x1026 formula units d) 1.74x1026 formula units e) none of the answers

The ratio of mass percent of C and H of an organic compound (CxHyOz) is 6 : 1. If one molecule of the above compound ( CxHyOZ ) contains half as much oxygen as required to burn one molecule of compound CXHY completely to CO2 and H2O. The empirical formula of compound CxHyOz is : (a) C2H4O (b) C3H4O2 (c) C2H4O3 (d) C3H6O3

The concentrated sulphuric acid that is peddled commercially is 95% H2SO4 by weight. If the density of this commercial acid is 1.834 g cm-3 , the molarity of this solution is :- (a) 17.8 M (b) 15.7 M (c) 10.5 M (d) 12.0 M

The compound formed in the positive test for nitrogen with the Lassaigne solution of an organic compound is (a) Fe4[Fe(CN)6]3 (b) Na4[Fe(CN)5NOS] (c) Fe(CN)3 (d) Na3[Fe(CN)6]

The density of a solution prepared by dissolving 120 g of urea (mol. mass = 60 u) in 1000 g of water is 1.15 g/mL. The molarity of this solution is (a) 2.05 M (b) 0.50 M (c) 1.78 M (d) 1.02 M

0.6 g of urea on strong heating with NaOH evolves NH3. Liberated NH3 will combine with which of the following HCl solution? (a) 100 mL of 0.2 N HCl (b) 400 mL of 0.2 N HCl (c) 100 mL of 0.1 N HCl (d) 200 mL of 0.2 N HC

For the reaction A + 2B C, rate is given by R = [A] [B]2 then the order of the reaction is (a) 3 (b) 6 (c) 5 (d) 7

The half-life period of a first-order chemical reaction is 6.93 minutes. The time required for the completion of 99% of the chemical reaction will be (log 2 = 0.301): (a) 46.06 minutes (b) 460.6 minutes (c) 230.3 minutes (d) 23.03 minutes