Recent questions in Chemistry

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1 answer 11 views

How can computational chemistry be used to design new metal-organic frameworks with optimal properties for carbon capture and storage?

asked Jan 22 in Computational Chemistry by MagnoliaReve (390 points)

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1 answer 56 views

How does increasing the temperature affect the rate of reaction between sodium thiosulfate and hydrochloric acid?

asked Jan 22 in Chemical kinetics by DannLennon19 (290 points)

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1 answer 60 views

A chemical mixture containing 30% ethanol and 70% water needs to be separated using a distillation column. The feed rate is 1000 kg/hr and the desired purity for both products is 99%. The distillation column has 20 theoretical trays, and the reflux ratio is 2.5. Determine the number of trays required to achieve the desired purity for both products.

asked Jan 22 in Chemical engineering by JaquelineGel (450 points)

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1 answer 10 views

A chemical engineering firm has been tasked with designing a chemical reactor for the synthesis of ammonia gas from nitrogen and hydrogen gases. The plant requires a production of at least 1000 kg/h of ammonia gas, and the reactor should operate at a pressure of 200 atm and a temperature of 400°C. The student should determine the optimal size and design of the reactor by considering the reaction kinetics, thermodynamics, and fluid dynamics principles. The student should also select appropriate catalysts and determine the flow rate of the reactants required to achieve the desired production rate.

asked Jan 22 in Chemical engineering by HowardMedley (270 points)

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1 answer 66 views

A chemical engineering company has a mixture of ethanol and water with a concentration of 30% ethanol to separate using a distillation column. The company needs to obtain a concentration of 80% ethanol in the distillate at a reflux ratio of 3. Calculate the number of theoretical plates required in the column for the separation, assuming no vapor or liquid bypass, and that the minimum vapor velocity is maintained.

asked Jan 22 in Chemical engineering by BrittCouture (650 points)

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1 answer 76 views

A chemical engineer wants to separate a mixture of ethanol and methanol using a distillation column. The feed to the column contains 30% ethanol and 70% methanol by mole. The engineer wants to obtain a distillate with 80% ethanol and a bottoms product containing no more than 1% ethanol. Determine the number of trays required in the distillation column to achieve this separation. Consider only equilibrium stages and assume that the feed is saturated liquid at its boiling point. The operating pressure of the column is 1 atm.

asked Jan 22 in Chemical engineering by JuniorReyes (330 points)

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1 answer 31 views

A chemical engineer needs to separate a mixture of ethanol and water using a distillation column. The feed to the column has 30 mol% ethanol and 70 mol% water, and the desired distillate composition is 95 mol% ethanol. The feed rate is 100 kmol/hour and the reflux ratio is 2. Calculate the number of theoretical trays required in the column to achieve the desired distillate composition.

asked Jan 22 in Chemical engineering by CarriHarbiso (430 points)

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1 answer 67 views

A chemical engineer needs to design a distillation column for the separation of a mixture containing ethanol (boiling point of 78.4°C) and water. The desired composition of the distillate is a minimum of 90% ethanol. What is the minimum number of theoretical trays needed in the column to achieve this composition, given that the feed contains 40% ethanol and the reflux ratio is 1.5?

asked Jan 22 in Chemical engineering by ConcettaL187 (230 points)

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1 answer 51 views

A certain polymerization reaction has a ΔH°rxn of -250 kJ/mol. If you need to make 500 grams of the polymer, how much energy in kilojoules will be released or absorbed during the reaction?

asked Jan 22 in ThermoChemistry by MinervaRico (370 points)

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1 answer 61 views

A certain metal oxide has an enthalpy of formation of -589.3 kJ/mol. When a 5.60 g sample of this oxide is reduced with excess hydrogen gas, the enthalpy change for the reaction is found to be -129.3 kJ/mol. Calculate the enthalpy of reduction per mole of this oxide.

asked Jan 22 in ThermoChemistry by JonasMcCarty (350 points)

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1 answer 69 views

A certain hydrocarbon requires 343 kJ of energy to break one mole of carbon-carbon bonds and 413 kJ/mole to break one mole of carbon-hydrogen bonds. What is the bond dissociation energy of the carbon-carbon and carbon-hydrogen bonds in this hydrocarbon?

asked Jan 22 in ThermoChemistry by RJKYukiko29 (390 points)

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1 answer 72 views

A certain chemical reaction has a delta H value of -120 kJ/mol. If 2.5 moles of this reactant undergo the reaction, how much energy is released or absorbed by the reaction?

asked Jan 22 in ThermoChemistry by DonCorral32 (350 points)

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1 answer 66 views

A brass alloy electrode with an area of 5 cm² is immersed in a 0.5 M NaCl solution at 25°C. Given that the standard potential of the electrode is -0.35 V versus a standard hydrogen electrode, calculate the corrosion current density of the electrode in the given environment using Tafel extrapolation.

asked Jan 22 in ElectroChemistry by SusanBellew (490 points)

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1 answer 88 views

A bottle contains a mixture of nitrogen and oxygen gases. At a specific temperature and pressure, the nitrogen molecules move on an average velocity of 500 m/s and oxygen molecules move at 400 m/s. What is the partial pressure of nitrogen and oxygen in the mixture if the total pressure of the gas is 1 atm?

asked Jan 22 in Physical Chemistry by Adele93T9749 (290 points)

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1 answer 67 views

A beaker of water is placed on a hot plate, and the temperature is gradually increased. Write an equation for the rate of change of entropy with respect to time during this process, assuming the system is not in equilibrium. Use the equation to determine the rate of entropy production in the water as it is heated from 25°C to 100°C at a constant rate of 2°C/min.

asked Jan 22 in Physical Chemistry by MargueriteBa (730 points)

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1 answer 83 views

A beaker containing 1L of water is divided into two equal compartments by a semi-permeable membrane. One side of the membrane has 1M NaCl solution and the other side is pure water. Determine the time taken for the concentration of NaCl on both sides of the membrane to become equal through diffusion. Given: Molecular weight of NaCl is 58.44 g/mol, and diffusion coefficient of NaCl in water is 1.6 x 10^-9 m^2/s.

asked Jan 22 in Physical Chemistry by GabriellaJai (330 points)

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1 answer 64 views

A battery consists of a Zinc electrode and a Copper electrode. Calculate the exchange current density at the Zinc electrode if the concentration of Zinc ion in its solution is 0.1 M and the potential difference between the electrodes is 1.5 V. The standard electrode potential for Zinc is -0.76 V and the transfer coefficient for the electrode reaction is 0.5.

asked Jan 22 in ElectroChemistry by NickiWhiddon (130 points)

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1 answer 90 views

A 50.0 g sample of ethanol is heated from 25.0 °C to 85.0 °C, and absorbs 237 J of heat. What is the specific heat capacity of ethanol?

asked Jan 22 in ThermoChemistry by BruceReece0 (330 points)

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1 answer 72 views

A 50 mL solution of 0.1 M Cu(NO3)2 was electrolyzed for 20 minutes. During this time, a current of 0.5 A was passed through the solution. What is the final concentration of Cu2+ ions in the solution after the electrolysis?

asked Jan 22 in ElectroChemistry by MarilouArnde (330 points)

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1 answer 69 views

A 5 g sample of a mixture containing sand and salt is dissolved in water. The solution is filtered, and the sand is collected and dried. The dried sand has a mass of 3 g. Using mass balance calculations, determine the percentage of salt in the original mixture.

asked Jan 22 in Analytical Chemistry by AnnmarieNune (750 points)

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