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Calculate the amount of heat energy needed to melt a 25-g ice cube at its melting point of 0°C. The enthalpy of fusion of water is 6.01 kJ/mol.

asked Jan 23 in ThermoChemistry by NelleVxq8414 (1.5k points)

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Calculate the enthalpy change of the polymerization reaction of ethylene, given that the heat of combustion of ethylene is -1411 kJ/mol and the enthalpy of formation of ethylene is +52.3 kJ/mol. The balanced equation for the polymerization of ethylene is:nC2H4 -> [-C2H4-]nAssume complete polymerization and that the standard enthalpy of formation of the polymer is negligible.

asked Jan 23 in ThermoChemistry by MeaganCramp (1.8k points)

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Calculate the enthalpy change for the combustion of methane gas (CH4) at standard conditions given the following information: 4 moles of methane gas is burned in excess oxygen gas (O2) to form carbon dioxide gas (CO2) and liquid water (H2O). The enthalpy change for the combustion of 1 mole of methane gas is -890.4 kJ/mol.

asked Jan 23 in Chemical thermodynamics by ChanteStroh (1.5k points)

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Calculate the bond order and bond length of the O-O bond in hydrogen peroxide (H2O2)? Show your work and explain your reasoning.

asked Jan 23 in Inorganic Chemistry by BrentAshcrof (1.5k points)

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1 answer 94 views

A chemistry student added 2 grams of sodium hydroxide to 50 ml of hydrochloric acid with a concentration of 0.5 M. After the reaction was complete, the student collected 1.5 grams of sodium chloride. Calculate the percent yield of sodium chloride.

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

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Calculate the bond dissociation energy (in kJ/mol) for the carbon-hydrogen bond in methane (CH4) using the following information: - The enthalpy change for the reaction CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) is -890.3 kJ/mol. - The enthalpy change for the reaction 2H2(g) + O2(g) → 2H2O(g) is -484.2 kJ/mol.

asked Jan 23 in ThermoChemistry by JordanChun58 (2.3k points)

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1 answer 47 views

Calculate the enthalpy change of ionization for magnesium given the following data: Mg(g) → Mg+(g) + e- ΔH1 = +738 kJ/mol Mg+(g) → Mg2+(g) + e- ΔH2 = +1451 kJ/mol

asked Jan 23 in ThermoChemistry by Georgianna69 (2.2k points)

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1 answer 93 views

A chemistry student is given the following thermochemical equations: Equation 1: H2 (g) + 1/2O2 (g) → H2O(l) ΔH1 = -285.8 kJ/mol Equation 2: C(s) + O2 (g) → CO2 (g) ΔH2 = -393.5 kJ/mol Equation 3: 2H2 (g) + O2 (g) → 2H2O(l) ΔH3 = -571.6 kJ/mol Using Hess's Law, calculate the enthalpy change for the following reaction: C(s) + 2H2 (g) → CH4 (g)

asked Jan 22 in ThermoChemistry by IsraelSeidel (1.3k points)

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1 answer 46 views

Calculate the enthalpy of adsorption of methane gas on activated charcoal at room temperature (25°C) given the following information:- The saturation pressure of methane at 25°C is 3.78 MPa.- The surface area of activated charcoal used is 100 m²/g.- The amount of methane adsorbed on the activated charcoal is 5 mmol/g.

asked Jan 23 in ThermoChemistry by IvyHogan8844 (1.6k points)

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1 answer 92 views

A chemistry student needs to determine the direction in which equilibrium will shift when the concentration of reactants in a reversible reaction is changed using Le Chatelier's principle. Given the reaction equation: 2SO2(g) + O2(g) ⇄ 2SO3(g), if the concentration of SO2 is increased, will the reaction shift to the left or right?

asked Jan 22 in Chemical reactions by YOKIva496594 (2.6k points)

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1 answer 52 views

Calculate the change in entropy of the system when 2 moles of ammonia react to form 3 moles of hydrogen gas and 1 mole of nitrogen gas. The reaction takes place at a constant temperature of 298 K and at a pressure of 1 atm. The molar entropy of each component in the reaction is given below:Ammonia: 192.5 J/K·molHydrogen gas: 130.6 J/K·molNitrogen gas: 191.6 J/K·mol

asked Jan 23 in Chemical thermodynamics by TinaKesler6 (1.9k points)

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1 answer 92 views

A chemistry student needs to determine the conditions at which a pure substance will change from solid to liquid phase. The substance in question has a melting point of 120 °C and a heat of fusion of 35 kJ/mol. How much heat is required to melt 100 grams of the substance at its melting point? And, what is the temperature at which the substance will start to solidify if the ambient pressure is 1 atm and the substance has cooled from its liquid phase at 150 °C to its solid phase?

asked Jan 22 in Physical Chemistry by EusebiaGilla (1.8k points)

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1 answer 92 views

A chemistry student needs to determine the composition of a sample that contains an unknown mixture of sodium chloride (NaCl) and potassium chloride (KCl). The student weighs 2.00 g of the mixture and dissolves it in water to obtain a solution. The student then precipitates the chloride ions from the solution with excess silver nitrate (AgNO3) to obtain 6.50 g of silver chloride (AgCl). Using mass balance calculations, determine the mass and percentage composition of the sodium chloride and potassium chloride in the mixture.

asked Jan 22 in Analytical Chemistry by KreogMoore5 (6.4k points)

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1 answer 44 views

Calculate the enthalpy of desorption of hydrogen gas (H2) from a platinum surface, given that the temperature of the surface is 298 K and the pressure of H2 gas above the surface is 1 atm. The adsorption enthalpy of H2 on Pt is -43300 J/mol. (Assume ideal gas behavior for H2.)

asked Jan 23 in ThermoChemistry by TahliaEvatt8 (2.2k points)

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1 answer 51 views

Calculate the current density in an electrochemical cell if a current of 2.5 A is passed through a cell containing 0.150 L of a 0.250 M solution of CuSO4 for 2.00 hours. The cathodic half-reaction is Cu2+ + 2e- → Cu and the anodic half-reaction is Zn → Zn2+ + 2e-. The cell has a standard potential of 1.10 V at 298 K. What is the current density of the cell?

asked Jan 23 in ElectroChemistry by AmyNowland4 (2.5k points)

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1 answer 53 views

Calculate the bond dissociation energy of the nitrogen-nitrogen (N-N) bond in N2O4 given that the enthalpy change for the reaction 2N2O4(g) --> 4NO2(g) is -109.7 kJ/mol.

asked Jan 23 in ThermoChemistry by OtisMacGilli (2.0k points)

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1 answer 39 views

Calculate the entropy change of the following reaction at 25°C and 1 atm pressure:2NH3(g) + 3Cl2(g) → N2(g) + 6HCl(g)Given the standard entropy values are:ΔS°NH3 = 192.5 J/K•molΔS°Cl2 = 223.1 J/K•molΔS°N2 = 191.6 J/K•molΔS°HCl = 186.9 J/K•mol

asked Jan 23 in Chemical thermodynamics by KatieManzi6 (1.6k points)

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1 answer 51 views

Calculate the corrosion rate of a copper metal when it is placed in a galvanic couple with zinc metal. The potential difference between the two metals is measured to be 1.5 V and the surface area of the copper metal is 2 cm². The density of copper is 8.96 g/cm³ and its atomic weight is 63.546 g/mol. The atomic weight of zinc is 65.38 g/mol and its density is 7.14 g/cm³. At constant temperature and pressure, assume that the Faraday constant is 96,485 Coulombs/mol and that one mole of electrons is equivalent to one Faraday.

asked Jan 23 in ElectroChemistry by TiffaniWymar (1.6k points)

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1 answer 93 views

A chemistry student has a sample of an unknown compound containing carbon, hydrogen, and oxygen. The mass of the sample is 2.50 g. After combustion, the student finds that 1.80 g of carbon dioxide, 0.75 g of water, and 0.20 g of oxygen are produced. Using mass balance calculations, determine the empirical formula of the unknown compound.

asked Jan 22 in Analytical Chemistry by Shelia708886 (2.1k points)

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1 answer 84 views

A student is studying the overpotential in an electrochemical reaction in a laboratory experiment. The student measures a current of 2.1 A at an electrode potential of -0.6 V, and 1.95 A at -0.5 V. What is the overpotential of the reaction?

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

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