Recent questions in Chemistry

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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 NannetteBene (450 points)

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1 answer 41 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 CarmaDelling (470 points)

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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 SharylHaskin (510 points)

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1 answer 45 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 ErnestoWakef (250 points)

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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 Kami22A8614 (490 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 VivienBeauch (490 points)

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1 answer 47 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 PoppyMcAdams (330 points)

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1 answer 36 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 ZacharyPluml (330 points)

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1 answer 60 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 DeanaSears12 (390 points)

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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 NganHendrick (490 points)

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1 answer 41 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 Sammy51U3823 (470 points)

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1 answer 37 views

A 25 mL solution of 0.1 M AgNO3 is mixed with a 50 mL solution of 0.05 M NaCl. What is the mass of AgCl that will be produced if a reaction occurs? (Assume the reaction goes to completion.)

asked Jan 22 in Chemical reactions by BretShattuck (390 points)

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1 answer 37 views

A 25 g sample of water at 25°C is heated by 200 J. The temperature of the water increases to 40°C. Calculate the specific heat capacity of water.

asked Jan 22 in Chemical thermodynamics by KateNewcombe (490 points)

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1 answer 53 views

A 2.5 L container was initially filled with 0.1 M solution of nitrogen dioxide which decomposes into nitrogen monoxide and oxygen gas according to the following reaction:2NO2(g) ⇌ 2NO(g) + O2(g)After the system has reached equilibrium, the concentration of nitrogen monoxide is found to be 0.05 M. What is the equilibrium concentration of oxygen gas in the container?

asked Jan 22 in Chemical equilibrium by JulietaLudlu (430 points)

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1 answer 48 views

A 15.0 g sample of a mixture containing sodium chloride and sodium nitrate is dissolved in water, and then silver nitrate is added until no more precipitation occurs. The mass of the precipitate is found to be 20.4 g. What is the mass percentage of each component in the mixture?

asked Jan 22 in Analytical Chemistry by VeronaRosas0 (450 points)

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1 answer 58 views

A 1.00 gram sample of sucrose (C12H22O11) is completely hydrolyzed in solution with excess HCl. If the solution is cooled to room temperature, what is the change in enthalpy ($\Delta H$) for the reaction? The heat capacity of the solution is 4.18 J/(g*K) and the temperature change is -10°C.

asked Jan 22 in ThermoChemistry by RyanAskins6 (650 points)

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1 answer 57 views

A 0.50 L vessel contains 1.0 mol of N2(g) and 3.0 mol of H2(g) at equilibrium at 400 K according to the following equation:N2(g) + 3H2(g) ⇌ 2NH3(g)If the volume of the vessel is suddenly decreased to 0.25 L, what will happen to the equilibrium position? Will the concentration of NH3 increase or decrease? Calculate the new equilibrium constant at this new volume.

asked Jan 22 in Chemical equilibrium by LeeIbx88687 (430 points)

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1 answer 59 views

A 0.25 mol/L solution of ethanoic acid (CH3COOH) is mixed with a 0.40 mol/L solution of sodium acetate (CH3COONa). The equilibrium constant for the reaction CH3COOH + NaCH3COO ⇌ CH3COONa + H2O is 1.8 x 10^-5. What is the concentration of CH3COONa at equilibrium?

asked Jan 22 in Chemical equilibrium by NormanMoowat (330 points)

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1 answer 52 views

A 0.1 M solution of ammonia (NH3) has a pH of 11.64 at room temperature. If sodium hydroxide (NaOH) is added to this solution such that the concentration of OH- ions becomes 0.01 M, what will be the new pH of the solution? (Assume that the dissociation of water can be ignored)

asked Jan 22 in Chemical equilibrium by NevaTegg7848 (450 points)

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1 answer 45 views

How would adding more reactants to a reaction at equilibrium affect the direction of the reaction and the equilibrium position, and what would be the quantitative effect on the equilibrium constant?

asked Jan 22 in Chemical equilibrium by EstebanBarra (210 points)

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