CHEMISTRY COMMUNITY

Steve Magana 2I

Question: In some reactions, two or more different products can be formed by different pathways. If the product formed by the faster reaction predominates, the reaction is considered to be under kinetic control. If the predominant product is the more thermodynamically stable, the reaction is conside...

Steve Magana 2I

Question: Determine which of the following statements about catalysts are true. If the statement is false, explain why. (a) In an equilibrium process, a catalyst increases the rate of the forward reaction but leaves the rate of the reverse reaction unchanged. (b) A catalyst is not consumed in the co...

Steve Magana 2I

Question: Indicate whether each of the following statements is true or false. If a statement is false, explain why. (a) For a reaction with a very large equilibrium constant, the rate constant of the forward reaction is much larger than the rate constant of the reverse reaction. (b) At equilibrium, ...

Steve Magana 2I

Question: When 0.52 g of H2 and 0.19 g of I2 are confined to a 750.-mL reaction vessel and heated to 700. K, they react by a second-order process (first order in each reactant), with k = 0.063 L.mol^-1.s^-1 in the rate law (for the rate of formation of HI). (a) What is the initial reaction rate? (b)...

Steve Magana 2I

Question: Express the units for rate constants when the concentrations are in moles per liter and time is in seconds for (a) zero-order reactions; (b) first-order reactions; (c) second- order reactions.

I'm having trouble with part c, can someone help me? Thank you!

Steve Magana 2I

Question: Ethene is a minor but important component of natural gas, and its combustion has been thoroughly studied. At a certain temperature and pressure, the unique rate of the combustion reaction C2H4(g) + 3 O2(g) --> 2 CO2(g) + 2 H2O(g) is 0.44 mol.L^-1.s^-1. (a) What is the rate at which oxygen ...

Steve Magana 2I

Question: Indicate for each of the following statements whether it applies to Eenodecell, to Ecell, to both, or to neither: (a) decreases as the cell reaction progresses; (b) changes with temperature; (c) doubles when the coefficients of the equation are doubled; (d) can be calculated from K; (e) is...

Steve Magana 2I

Question: (a) The standard Gibbs free energy of formation of Tl^3+(aq) is +215 kJ.mol^-1 at 25 degrees Celsius. Calculate the standard potential of the Tl^3+/Tl couple. (b) Will Tl^+ disproportionate in aqueous solution? For part b, how would you determine if something will disproportionate? Thank y...

Steve Magana 2I

Question: A certain enzyme-catalyzed reaction in a biochemical cycle has an equilibrium constant that is 10 times the equilibrium constant of the next step in the cycle. If the standard Gibbs free energy of the first reaction is -200. kJ.mol^-1, what is the standard Gibbs free energy of the second r...

Steve Magana 2I

Question: Arrange the following metals in order of increasing strength as reducing agents for species in aqueous solution: (a) Cu, Zn, Cr, Fe; (b) Li, Na, K, Mg; (c) U, V, Ti, Al; (d) Ni, Sn, Au, Ag.

How does one determine the strength of each element in these cases? Thank you!

Steve Magana 2I

Question: A student was given a standard Cu(s) 0 Cu2+(aq) half-cell and another half-cell containing an unknown metal M immersed in 1.00 m M(NO3)2(aq). When the copper was connected as the anode at 25 degrees Celsius, the cell potential was found to be -0.689 V. What is the reduction potential for t...

Steve Magana 2I

Question: Which of the following compounds become less stable with respect to the elements as the temperature is raised: (a) PCl5(g); (b) HCN(g); (c) NO(g); (d) SO2(g)?

Can someone help me with understanding this question please? Thank you!

Steve Magana 2I

Question: Which would you expect to have a higher molar entropy at T = 0, single crystals of BF3 or of COF2? Why?

Can someone help me with this question please? Thank you!

Steve Magana 2I

Question: Calculate the standard entropy of vaporization of water at 85 degrees Celsius, given that its standard entropy of vaporization at 100. degrees Celsius is 109.0 J.K^-1.mol^-1 and the molar heat capacities at constant pressure of liquid water and water vapor are 75.3 J.K^-1.mol^-1 and 33.6 J...

Steve Magana 2I

Question: During the test of an internal combustion engine, 3.00 L of nitrogen gas at 18.5 degrees Celsius was compressed suddenly (and irreversibly) to 0.500 L by driving in a piston. In the process, the temperature of the gas increased to 28.1 degrees Celsius. Assume ideal behavior. What is the ch...

Steve Magana 2I

Question: The reaction of 1.40 g of carbon monoxide with excess water vapor to produce carbon dioxide and hydrogen gases in a bomb calorimeter causes the temperature of the calorimeter assembly to rise from 22.113 degrees Celsius to 22.799 degrees Celsius. The calorimeter assembly is known to have a...

Steve Magana 2I

Question: How much heat is needed to convert 80.0 g of ice at 0.0 degrees Celsius into liquid water at 20.0 degrees Celsius?

I'm having trouble understanding this question and what to do. Thank you!

Steve Magana 2I

Question: (a) Calculate the heat that must be supplied to a 500.0-g copper kettle containing 400.0 g of water to raise its temperature from 22.0 degrees Celsius to the boiling point of water, 100.0 degrees Celsius. (b) What percentage of the heat is used to raise the temperature of the water? I'm ha...

Steve Magana 2I

Question: Determine the reaction enthalpy for the hydrogenation of ethyne to ethane, C2H2(g) + 2 H2(g) --> C2H6(g), from the following data: deltaHc(C2H2, g) = -1300. kJ/mol, deltaHc(C2H6, g) = -1560. kJ/mol, deltaHc(H2, g) = -286 kJ/mol. I was able to do this problem, but my answer does not match t...

Steve Magana 2I

Question: Air in a bicycle pump is compressed by pushing in the handle. If the inner diameter of the pump is 3.0 cm and the pump is depressed 20. cm with a pressure of 2.00 atm, (a) how much work is done in the compression? (b) Is the work positive or negative with respect to the air in the pump? (c...

Steve Magana 2I

Question: Identify the following systems as open, closed, or isolated: (a) coffee in a very-high-quality thermos bottle; (b) coolant in a refrigerator coil; (c) a bomb calorimeter in which benzeneis burned; (d) gasoline burning in an automobile engine; (e) mercury in a thermometer; (f) a living plan...

Steve Magana 2I

Questions: 12.69 Calculate the pH of each of the following solutions: (b) 0.055 m AlCl3(aq).

Can someone help me with this question please? Thank you!

Steve Magana 2I

Question: 12.63 The percentage deprotonation of benzoic acid in a 0.110 m solution is 2.4%. What is the pH of the solution and the Ka of benzoic acid?

How do you go from deprotonation percentage to pH? Thank you!

Steve Magana 2I

Question: 12.61 Find the initial concentration of the weak acid or base in each of the following aqueous solutions: (a) a solution of HClO with pH = 4.60; (b) a solution of hydrazine, NH2NH2, with pH = 10.20.

I'm having trouble starting this question, can someone help please? Thank you!

Steve Magana 2I

Question: Calculate the pH of 0.15 m H2SO4(aq) at 25 degrees Celsius.

How would you know that the initial concentration of H30+ is also 0.15 mol/L? Thank you!

Steve Magana 2I

Question: Calculate the pH, pOH, and percentage deprotonation of each of the following aqueous solutions: (a) 0.20 m CH3COOH(aq); (b) 0.20 m CCl3COOH(aq); (c) 0.20 m HCOOH(aq). (d) Explain any differences in pH on the basis of molecular structure. For a question like this, how would you find the per...

Steve Magana 2I

Question: Arrange the following bases in order of increasing strength on the basis of the pKa values of their conjugate acids, which are given in parentheses: (a) ammonia (9.26); (b) methylamine (10.56); (c) ethylamine (10.81); (d) aniline (4.63). I'm really confused with this question and pKa/pKb i...

Steve Magana 2I

Question:Predict whether each of the following equilibria will shift toward products or reactants with a temperature increase: (a) N2O4(g) <--> 2 NO2(g), ΔH = +57 kJ (b) X2(g) <--> 2 X(g), where X is a halogen (c) Ni(s) + 4 CO(g) <--> Ni(CO)4(g), ΔH = -161 kJ (d) CO2(g) + 2 NH3(g) <--> CO(NH2)2(s) +...

Steve Magana 2I

Question: Consider the equilibrium 3 NH3(g) + 5 O2(g) <---> 4 NO(g) + 6 H2O(g). (a) What happens to the partial pressure of NH3 when the partial pressure of NO is increased? (b) Does the partial pressure of O2 decrease when the partial pressure of NH3 is decreased? Can someone help me with this plea...

Steve Magana 2I

Question: A 0.10-mol sample of pure ozone, O3, is placed in a sealed 1.0-L container and the reaction 2 O3(g) <---> 3 O2(g) is allowed to reach equilibrium. A 0.50-mol sample of pure ozone is placed in a second 1.0-L container at the same temperature and allowed to reach equilibrium. Without doing a...

Steve Magana 2I

Question: In each of the following salts, either the cation or the anion is a weak acid or a weak base. Write the chemical equation for the proton transfer reaction of this cation or anion with water: (a) NaC6H5O; (b) KClO; (c) C5H5NHCl; (d) NH4Br. I'm having trouble coming up with the equations and...

Steve Magana 2I

Question: Suggest an explanation for the different strengths of (a) acetic acid and trichloroacetic acid; (b) acetic acid and formic acid.

Can someone explain the answers for both parts please? Thank you!

Steve Magana 2I

Question: Which is the stronger base, the hypobromite ion, BrO^-, or morphine, C17H19O3N? Justify your answer.

Can someone explain this question to me please? Thank you!

Steve Magana 2I

Question: Which of the following reactions can be classified as reactions between Brønsted acids and bases? For those that can be so classified, identify the acid and the base. (Hint: It may help to write the net ionic equations.) (a) NH4I(aq) + H2O(l) --> NH3(aq) + H3O(aq) + I(aq) (b) NH4I(s) --> N...

Steve Magana 2I

Question: Which of the following ligands can be polydentate? If the ligand can be polydentate, give the maximum number of places on the ligand that can bind simultaneously to a single metal center: (a) HN(CH2CH2NH2)2; (b) CO3^2-; (c) H2O; (d) oxalate. I having trouble answering this, can someone gui...

Steve Magana 2I

Question: Benzyne, C6H4, is a highly reactive molecule that is detected only at low temperatures. It is related to benzene in that it has a six-membered ring of carbon atoms; but, instead of three double bonds, the structure is normally drawn with two double bonds and a triple bond. (a) Draw a Lewis...

Steve Magana 2I

Question: State the relative orientations of the following hybrid orbitals: (a) sp3; (b) sp; (c) sp3d2; (d) sp2.

What does it mean by stating the relative orientations? Thank you!

Steve Magana 2I

Question: Describe the structure of the formaldehyde molecule, CH2O, in terms of hybrid orbitals, bond angles, and sigma and pi bonds. The C atom is the central atom to which the other three atoms are attached.

I am confused on how I would describe this, can someone help on this? Thank you!

Steve Magana 2I

Question: Noting that the bond angle of an sp3 hybridized atom
is 109.5 and that of an sp2 hybridized atom is 120, do you expect the bond angle between two hybrid orbitals to increase or decrease as the s-character of the hybrids is increased?

Can someone help me with this question please? Thank you!

Steve Magana 2I

Question: For which of the following molecules will dipole–dipole interactions be important: (a) CH4; (b) CH3Cl; (c) CH2Cl2; (d) CHCl3; (e) CCl4?

Can someone explain how you would know if the interaction is important? Thank you!

Steve Magana 2I

Question: Account for the following observations in terms of the type and strength of intermolecular forces. (a) The melting point of solid xenon is -112 Celsius and that of solid argon is -189 Celsius. (b) The vapor pressure of diethyl ether (C2H5OC2H5) is greater than that of water. (c) The boilin...

Steve Magana 2I

Question: Suggest, giving reasons, which substance in each of the following pairs is likely to have the higher normal melting point (Lewis structures may help your arguments): (a) HCl or NaCl; (b) C2H5OC2H5 (diethyl ether) or C4H9OH (butanol); (c) CHI3 or CHF3; (d) C2H4 or CH3OH. How would you even ...

Steve Magana 2I

Question: Which do you predict to have the strongest CX bond, where X is a halogen: (a) CF4, (b) CCl4, or (c) CBr4 ? Explain.

How do you approach this problem and what is it asking? Thank you!

Steve Magana 2I

Question: Arrange the cations Rb^+, Be^2+, and Sr^2+ in order of increasing polarizing power. Give an explanation of your arrangement.

Can someone explain the explanation for the arrangement? Thank you!

Steve Magana 2I

Question: Compounds having bonds with a high covalent character tend to be less soluble in water than similar compounds that have low covalent character. Use electronegativities to predict which of the following compounds is the more soluble in water: (a) AlCl3 or KCl; (b) MgO or BaO. Can someone ex...

Steve Magana 2I

Question: Why are s-block metals typically more reactive than p-block metals?

Can someone explain the concept behind this please? Thank you!

Steve Magana 2I

Question: Which of the following species are radicals? (a) NO2; (b) CH3; (c) OH; (d) CH2O.

Can someone explain to me what are radicals please? Thank you!

Steve Magana 2I

Question: Chlorine can exist in both positive and negative oxidation states. What is the maximum (a) positive and (b) negative oxidation number that chlorine can have? (c) Write the electron configuration for each of these states. (d) Explain how you arrived at these values. Can someone please help ...

Steve Magana 2I

Question: Ionization energies usually increase on going from left to right across the periodic table. The ionization energy for oxygen, however, is lower than that of either nitrogen or fluorine. Explain this anomaly.

Can someone explain why? Thank you!

Steve Magana 2I

Question: Which of the following increase when an electron in a lithium atom undergoes a transition from the 1s-orbital to a 2p-orbital? (a) Energy of the electron. (b) Value of n. (c) Value of l. (d) Radius of the atom.

Can someone please explain why they all increase? Thank you!

Steve Magana 2I

Question: A lamp rated at 32 W (1 W = 1 J.s^-1) emits violet light of wavelength 420 nm. How many photons of violet light can the lamp generate in 2.0 s? How many moles of photons are emitted in that time interval? I was wondering if someone can help me see what I've been doing wrong because I keep ...

Steve Magana 2I

Question: In a recent suspense film, two secret agents must penetrate a criminal’s stronghold monitored by a lithium photomultiplier cell that is continually bathed in light from a laser. If the beam of light is broken, an alarm sounds. The agents want to use a handheld laser to illuminate the cell ...

Steve Magana 2I

Question: The energy required to break a C-C bond in a molecule is 348 kJ.mol^-1. Will visible light be able to break this bond? If yes, what is the color of that light? If not, what type of electromagnetic radiation will be suitable?

Does anyone know how to approach this problem? Thank you!

Steve Magana 2I

Question: Use the Rydberg formula for atomic hydrogen to calculate the wavelength of radiation generated by the transition from n = 4 to n = 2.

Can someone help me understand how to do this problem please? Thank you!

Steve Magana 2I

Question: A medical researcher investigating the properties of intravenous solutions prepared a solution containing 0.278 m C6H12O6 (glucose). What volume of solution should the researcher use to provide 4.50 mmol C6H12O6? My answer is not matching the correct one, so I was hoping I can get some gui...

Steve Magana 2I

Question: Sodium vapor lamps, used for public lighting, emit yellow light of wavelength 589 nm. How much energy is emitted by (a) an excited sodium atom when it generates a photon; (b) 5.00 mg of sodium atoms emitting light at this wavelength; (c) 1.00 mol of sodium atoms emitting light at this wave...

Steve Magana 2I

Question: Solve this exercise without using a calculator. The reaction 6 ClO2 + 2 BrF3 ----> 6 ClO2F + Br2 is carried out with 12 mol ClO2 and 5 mol BrF3. (a) Identify the excess reactant. (b) Estimate how many moles of each product will be produced and how many moles of the excess reactant will rem...

Steve Magana 2I

Question: A stimulant in coffee and tea is caffeine, a substance of molar mass 194 g.mol^-1. When 0.376 g of caffeine was burned, 0.682 g of carbon dioxide, 0.174 g of water, and 0.110 g of nitrogen were formed. Determine the empirical and molecular formulas of caffeine, and write the equation for i...

Steve Magana 2I

Oops actually Cl2 is the limiting reactant, I accidentally mixed up the results I had calculated with Al.

Steve Magana 2I

Question: Aluminum metal reacts with chlorine gas to produce aluminum chloride. In one preparation, 255 g of aluminum is placed in a container holding 535 g of chlorine gas. After reaction ceases, it is found that 300. g of aluminum chloride has been produced. (a) Write the balanced equation for the...

Steve Magana 2I

Question: Calculate the amount (in moles) of H2O in 2.00 g of Na2CO3 x 10H2O

How would you approach this problem? The multiplication sign is what specifically throws me off. Thank you!

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