Recent questions in Chemistry

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1 answer 85 views

A student performed an experiment in which 2.1 moles of nitrogen and 0.8 moles of hydrogen react to form ammonia gas. If the equilibrium constant for the reaction is 3.5 x 10^-4 at a certain temperature, what is the equilibrium concentration of ammonia?

asked Jan 22 in Chemical reactions by SherrylIwz83 (2.0k points)

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1 answer 101 views

A student needs to prepare a solution containing 50 g of ethanol (C2H5OH) dissolved in 250 g of water (H2O) at 25°C. Assuming the heat of mixing for ethanol and water is -5.02 kJ/mol, calculate the heat released or absorbed when the two substances are mixed. Express your answer in kJ.

asked Jan 22 in ThermoChemistry by CarmineGaric (2.1k points)

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0 answers 104 views

A student needs to prepare a solution containing 50 g of ethanol (C2H5OH) dissolved in 250 g of water (H2O) at 25°C. Assuming the heat of mixing for ethanol and water is -5.02 kJ/mol, calculate the heat released or absorbed when the two substances are mixed. Express your answer in kJ.

asked Jan 22 in ThermoChemistry by PalmaYuille (2.1k points)

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1 answer 129 views

A student needs to prepare a buffer solution with a pH of 7.20 using acetic acid (CH3COOH) and sodium acetate (NaCH3COO), with a total buffer concentration of 0.20 M. What mass of CH3COOH needs to be added to 200 mL of 0.10 M NaCH3COO to obtain the desired pH? (Ka of CH3COOH is 1.8x10^-5)

asked Jan 22 in Chemical reactions by TomokoSorian (2.2k points)

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1 answer 106 views

A student needs to prepare a buffer solution with a pH of 4.5 using acetic acid (pKa = 4.76) and its conjugate base sodium acetate. The student has 100 mL of 0.1 M acetic acid and has access to sodium acetate. What mass of sodium acetate (in grams) should the student add to the solution to achieve the desired pH?

asked Jan 22 in Chemical reactions by Maura45O7086 (2.5k points)

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1 answer 80 views

A student needs to prepare 500 mL of a buffer solution with a pH of 7.5 using a weak acid HA and its conjugate base A-. HA has a pKa of 4.5 and its initial concentration is 0.2 M. What mass of HA and A- should be mixed to prepare the buffer solution?

asked Jan 22 in Chemical reactions by DeenaTrundle (2.2k points)

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1 answer 80 views

A student needs to find the enthalpy of polymerization of ethylene from the enthalpies of combustion of ethylene gas (-1411 kJ/mol) and polyethylene (-5120 kJ/mol). Calculate the enthalpy change, in kJ/mol, for the polymerization of ethylene gas to form polyethylene.

asked Jan 22 in ThermoChemistry by TracieM73151 (2.5k points)

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1 answer 87 views

A student needs to find out how much heat is released or absorbed when 100 mL of 0.1 mol/L solution of barium chloride (BaCl2) is mixed with 150 mL of 0.1 mol/L solution of sodium sulfate (Na2SO4) at 25°C. Given the enthalpy of precipitation of BaSO4 as -256 kJ/mol, calculate the enthalpy change (in kJ) for the reaction that occurs and determine whether the reaction is exothermic or endothermic.

asked Jan 22 in ThermoChemistry by BrainRubin29 (2.2k points)

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1 answer 93 views

A student needs to determine the standard electrode potential for the following reaction: Fe3+ + e- → Fe2+ Using the standard electrode potentials of Fe3+/Fe2+ and Ag+/Ag, calculate the standard cell potential for the following reaction: 2Ag+ (aq) + Fe(s) → 2Ag(s) + Fe2+ (aq) Determine if this reaction is spontaneous or nonspontaneous under standard conditions.

asked Jan 22 in ElectroChemistry by GeraldoPatte (1.7k points)

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1 answer 93 views

A student needs to determine the mass of silver that can be deposited on a silver electrode using a current of 2.5 A for 3 hours in a solution containing 0.2 M silver ions. What is the mass of silver deposited on the electrode? (Assuming 100% current efficiency and atomic weight of silver is 107.9 g/mol)

asked Jan 22 in ElectroChemistry by MuhammadNuna (2.1k points)

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1 answer 68 views

A student needs to determine the enthalpy change of a chemical reaction using the Hess's Law equation. They have the following information:- The enthalpy change for Reaction 1 is -210 kJ/mol- The enthalpy change for Reaction 2 is -325 kJ/mol- The enthalpy change for Reaction 3 is 155 kJ/molThe student needs to use Hess's Law to calculate the enthalpy change for the following reaction:4A + 3B → 2CGiven the information above, what is the enthalpy change for the reaction?

asked Jan 22 in Chemical reactions by LamontMccror (1.9k points)

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1 answer 85 views

A student needs to determine the enthalpy change (ΔH) for the reaction between ammonium nitrate (NH4NO3) and water (H2O) using Hess's Law calculations. Given the following information: - ΔHf° (NH4NO3) = -365.4 kJ/mol- ΔHf° (HNO3) = -207.3 kJ/mol- ΔHf° (NH4+) = -132.5 kJ/mol- ΔHf° (NO3-) = -206.1 kJ/mol- ΔHf° (H2O) = -285.83 kJ/molFormulate the thermochemical equation for the reaction by using the given data and Hess's Law calculations, and then calculate the enthalpy change for the reaction.

asked Jan 22 in ThermoChemistry by LeannaCremea (1.6k points)

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1 answer 75 views

A student needs to determine the diffusion coefficient of a gas in a liquid by measuring the rate of diffusion using a diffusion cell. If the student knows the initial concentration and final concentration of the gas in the cell, and the time it took for diffusion to occur, what is the diffusion coefficient of the gas in the liquid?

asked Jan 22 in Physical Chemistry by MistyReagan2 (1.4k points)

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1 answer 86 views

A student needs to determine the diffusion coefficient of a gas at a given temperature and pressure using Graham's law of diffusion. The student has the necessary equipment to measure the rate of diffusion of the gas and the molecular weight of the gas is known. Determine the diffusion coefficient of the gas.

asked Jan 22 in Physical Chemistry by BradCoz53277 (1.9k points)

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1 answer 80 views

A student needs to determine the concentration of a sulfuric acid solution using a sodium hydroxide solution of known concentration. The student performs a titration and records that it took 27.5 milliliters of the sodium hydroxide solution to neutralize 25 milliliters of the sulfuric acid solution. What is the concentration (in moles per liter) of the sulfuric acid solution?

asked Jan 22 in Chemical reactions by DorieEverson (2.0k points)

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1 answer 65 views

A student needs to determine the change in enthalpy (ΔH) for the reaction between methane (CH4) and oxygen (O2) to form carbon dioxide (CO2) and water (H2O) at a temperature of 25°C and a pressure of 1 atm. The initial concentrations of CH4 and O2 are both 0.1 M, and the final concentrations of CO2 and H2O are both 0.05 M. What is the change in enthalpy for this reaction at the given conditions?

asked Jan 22 in Physical Chemistry by AveryJoris20 (2.0k points)

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1 answer 77 views

A student needs to determine the amount of copper present in a sample of brass using coulometry. If the sample is dissolved in acid and subjected to coulometric analysis using a standard silver electrode, what is the concentration of copper (in ppm) in the brass sample?

asked Jan 22 in Analytical Chemistry by MaybellHoffm (2.2k points)

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1 answer 31 views

A student needs to determine the activation energy for the electrochemical reaction between zinc and copper sulfate using the Arrhenius equation. The student has experimental data that includes the rate constants and temperatures at which the reaction was performed. Using the experimental data, the student needs to calculate the activation energy for the reaction and explain the significance of this value in terms of the reaction kinetics.

asked Jan 22 in ElectroChemistry by EdwinLindell (1.9k points)

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1 answer 77 views

A student needs to determine the activation energy for an electrochemical reaction involving the oxidation of Zinc using a voltage of 1.85V, a current of 0.25A and a temperature of 25°C. Given that the standard potential for this reaction at 25°C is -0.76V, what is the activation energy of the reaction?

asked Jan 22 in ElectroChemistry by KassieStarns (2.3k points)

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1 answer 81 views

A student needs to calculate the Tafel slopes for the anodic and cathodic reactions from a given set of experimental data obtained during an electrochemical experiment. The experiment involves the corrosion of iron in a solution with a pH of 3.5. The anodic and cathodic current densities were measured at various applied potentials ranging from -700 mV vs SHE to -400 mV vs SHE. The student needs to plot a Tafel plot for each reaction and calculate their corresponding Tafel slopes. Based on the obtained results, the student needs to explain the corrosion mechanism of iron in the given acidic solution.

asked Jan 22 in ElectroChemistry by BrentonMcQua (1.7k points)

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