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Can the chemical modification of a polymer affect its optical properties and if so, how can we design a polymer with unique optical properties for use in advanced optical materials?

asked Feb 3 in Polymer Chemistry by FrancineCron (1.6k points)

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Calculate the standard enthalpy change (∆H°) and standard entropy change (∆S°) for the reaction between solid aluminum and gaseous oxygen to form solid aluminum oxide, given the following balanced chemical equation:4Al(s) + 3O2(g) → 2Al2O3(s) The standard enthalpies of formation of Al(s), O2(g), and Al2O3(s) are -394.4 kJ/mol, 0 kJ/mol, and -1675.7 kJ/mol, respectively. The standard entropy change for the reaction of O2(g) to form Al2O3(s) is -159.6 J/K·mol.

asked Feb 3 in Inorganic Chemistry by LinCheatham (2.0k points)

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Calculate the standard enthalpy change for the following reaction: [CoCl(NH3)5]2+ (aq) + 4H2O (l) → [Co(H2O)6]2+ (aq) + 2Cl- (aq) + 5NH3 (g)Given that the standard enthalpy of formation of [Co(H2O)6]2+ (aq) is -1518.5 kJ/mol, [CoCl(NH3)5]2+ (aq) is -426.9 kJ/mol, and the enthalpy of vaporization of water is 44.0 kJ/mol.

asked Feb 3 in Chemical thermodynamics by HeleneHoward (2.0k points)

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How does changing the concentration of reactants affect the rate of a reaction with a multi-step reaction mechanism?

asked Feb 3 in Chemical kinetics by YvetteLink0 (2.0k points)

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Calculate the standard enthalpy change for the vaporization reaction of 2.00 moles of water at 100°C and 1 atm pressure, given that the molar enthalpy of vaporization of water is 40.7 kJ/mol.

asked Feb 3 in Chemical thermodynamics by 73351052550 (1.9k points)

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Consider an electrochemical cell containing a copper electrode in a 0.5 M CuSO4 solution and a silver electrode in a 1.0 M AgNO3 solution. Calculate the current density at a temperature of 25°C given that the copper electrode has a surface area of 5 cm² and the silver electrode has a surface area of 10 cm². The standard reduction potentials for Cu²⁺ and Ag⁺ are -0.34 V and 0.80 V, respectively. Use the Nernst equation to calculate the cell potential and then use Ohm's law to calculate the current density.

asked Feb 3 in ElectroChemistry by MarcyVallejo (2.2k points)

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What is the effect of changing the concentration of reactants on the reaction rate and yield of a chemical reaction?

asked Feb 3 in Chemical kinetics by DelilahKyte3 (1.8k points)

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1 answer 37 views

Design a heat exchanger for a chemical process that requires heating of 50 kg/hr of water from 25°C to 80°C using steam as the heating medium. The available steam is at a pressure of 1.5 MPa and a temperature of 300°C. The overall heat transfer coefficient between the water and the steam is 600 W/m2K. The heat exchanger should be designed to accommodate a temperature drop of 5°C for both the water and the steam. Determine the required surface area of the heat exchanger and the mass flow rate of steam required to meet the process requirements.

asked Feb 4 in Chemical engineering by FerminRosale (1.5k points)

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How can chemistry students be better prepared for chemistry-related careers to effectively apply their education and skills to real-world situations?

asked Feb 4 in Chemical education by MerissaGxv8 (1.7k points)

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Design a counter-current heat exchanger to cool 10,000 liters per hour of cyclohexane at 110°C down to 50°C, while heating 7,500 liters per hour of water at 25°C up to 80°C. The cyclohexane will be cooled by water which enters the heat exchanger at 90°C and exits at 60°C. The overall heat transfer coefficient is expected to be 1,000 W/m2K. Determine the required heat transfer area and the pressure drop across the heat exchanger.

asked Feb 3 in Chemical engineering by AltonDurden (2.1k points)

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Certainly! Here's a precise problem for the student to solve:Calculate the standard enthalpy change ($\Delta H^\circ$) for the dissolution reaction of 5.00 g of lithium chloride ($\text{LiCl}$) in 150.0 mL of water, given that the density of water is 1.00 g/mL and the final temperature of the solution is 25.0$^\circ$C. The molar enthalpy of solution of $\text{LiCl}$ is -3.00 kJ/mol.

asked Feb 3 in Chemical thermodynamics by OctaviaAbe18 (2.2k points)

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Calculate the standard enthalpy change for the reaction: 2 NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2 H2O(l)Given the following data:ΔHf°(NaOH) = -469.14 kJ/molΔHf°(H2SO4) = -814.00 kJ/molΔHf°(Na2SO4) = -1388.40 kJ/molΔHf°(H2O(l)) = -285.83 kJ/mol

asked Feb 3 in Chemical thermodynamics by BetteBoniwel (1.6k points)

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Consider the following chemical reaction: 2H2(g) + O2(g) ⇌ 2H2O(g)At a certain temperature and pressure, the partial pressures of H2, O2, and H2O are found to be 0.20 atm, 0.10 atm, and 0.80 atm, respectively. Calculate the reaction quotient (Qc) for this reaction at this temperature and pressure. Is the system at equilibrium? If not, in which direction will the reaction proceed to attain equilibrium?

asked Feb 3 in Chemical thermodynamics by DeloresQ3217 (1.6k points)

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Calculate the standard entropy change for the reaction: 2SO3(g) + O2(g) → 2SO4(g) Given the following standard entropies of formation: ΔS°f SO3(g) = 256.2 J/K mol ΔS°f O2(g) = 205.0 J/K mol ΔS°f SO4(g) = 296.8 J/K mol

asked Feb 3 in Inorganic Chemistry by GlenCaringto (2.1k points)

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Calculate the theoretical yield of benzocaine that can be produced from 1.5 moles of p-aminobenzoic acid and excess ethanol, assuming complete conversion and a 95% yield.

asked Feb 3 in Chemical synthesis by BradCoz53277 (1.9k points)

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Describe the role of the metal ion in the active site of metalloenzymes, using the coordination chemistry principles. Provide examples of metalloenzymes and their relevant metallic centers, and explain how the metal ion contributes to their function.

asked Feb 3 in Coordination Chemistry by LeoraHoag23 (1.7k points)

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1 answer 73 views

How does changing the molecular weight of a polymer affect its melt viscosity and how can this be quantitatively measured using rheological measurements such as shear rate and shear stress?

asked Feb 3 in Polymer Chemistry by JaneenBarrie (1.6k points)

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Calculate the standard enthalpy change for the reaction between methane and oxygen to form carbon dioxide and water vapor at 298 K and 1 atm of pressure, given the following reaction equation:CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)The standard enthalpies of formation for CH4(g), CO2(g), and H2O(g) are -74.8 kJ/mol, -393.5 kJ/mol, and -241.8 kJ/mol, respectively.

asked Feb 3 in Chemical thermodynamics by RemonaRainey (1.6k points)

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1 answer 57 views

Calculate the standard Gibbs free energy change for the following chemical reaction at 25°C:2H2(g) + O2(g) → 2H2O(l)The standard Gibbs free energy of formation at 25°C for H2O(l) is -237.2 kJ/mol, H2(g) is 0 kJ/mol, and O2(g) is 0 kJ/mol.

asked Feb 3 in Chemical thermodynamics by SZVRamon1645 (2.4k points)

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1 answer 61 views

Calculate the standard enthalpy change for the fusion reaction of 1 mole of ice at 0°C to 1 mole of liquid water at 0°C. Given the standard enthalpy of fusion of water is 6.02 kJ/mol and the specific heat capacity of water is 4.18 J/(g·°C).

asked Feb 3 in Chemical thermodynamics by LewisR691771 (1.8k points)

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