Recent questions in Chemistry

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Calculate the heat of formation of carbon dioxide (CO2) given the following information: heat of formation of C(graphite) = 0 kJ/mol, heat of formation of O2(g) = 0 kJ/mol, and heat of combustion of graphite = -393.5 kJ/mol.

asked Jan 23 in Chemical bonding by SalvatoreFre (310 points)

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Calculate the heat of formation of a water molecule from its elements, hydrogen and oxygen gas, given that the standard enthalpy of formation of hydrogen gas is -285.8 kJ/mol and the standard enthalpy of formation of oxygen gas is 0 kJ/mol. Show all your work and explain what the resulting sign of the enthalpy of formation means in terms of the stability of the water molecule.

asked Jan 23 in Chemical bonding by RileyBethune (350 points)

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Calculate the heat of formation for the compound methane (CH4) given that the enthalpy change for the reaction of carbon (C) with hydrogen gas (H2) to form methane gas (CH4) is -74.8 kJ/mol.

asked Jan 23 in Chemical bonding by Hilda5002237 (410 points)

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Calculate the heat of formation (ΔHf) of methane (CH4) given the following bond energies: C-C = 347 kJ/mol, C-H = 413 kJ/mol.

asked Jan 23 in Chemical bonding by GayePetheric (390 points)

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Calculate the heat of formation (∆Hf) of water (H2O) given the following reactions and their respective heats of reaction (∆Hr):2H2(g) + O2(g) → 2H2O(g); ∆Hr = -484 kJ/mol ½ O2(g) + H2(g) → H2O(l); ∆Hr = -285.8 kJ/mol Note: The heat of formation is the amount of heat released or absorbed when one mole of a compound is formed from its elements in their standard states.

asked Jan 23 in Chemical bonding by LinoShearer (510 points)

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1 answer 52 views

Calculate the heat of crystallization, in kilojoules per mole, when 50.0 grams of sodium hydroxide (NaOH) is dissolved in 500.0 grams of water at 25⁰C and then cooled to 5⁰C, assuming that all the heat evolved during the process is transferred to the solution. The heat capacity of water is 4.18 J/gK, and the enthalpy of formation of NaOH is -425 kJ/mol.

asked Jan 23 in ThermoChemistry by Bonita039700 (330 points)

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Calculate the heat of crystallization when 10.0 g of sodium acetate trihydrate (NaCH3COO.3H2O) is dissolved in 100.0 mL of water at 25°C and the solution is allowed to cool to 15°C. The specific heat capacity of the solution is 4.18 J/g °C and the density of the solution is 1.0 g/mL. The heat of solution of sodium acetate trihydrate is -7126 J/mol.

asked Jan 23 in ThermoChemistry by JacksonJonso (250 points)

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Calculate the heat of crystallization of NaOH given that 10 grams of NaOH dissolves in 100 mL of water at 25°C and the resulting solution is cooled to 0°C. The enthalpy of solution of NaOH is -44.5 kJ/mol, and the density of the resulting solution is 1.1 g/mL.

asked Jan 23 in ThermoChemistry by BernardoHamb (570 points)

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Calculate the heat of crystallization of NaCl if 1786 kJ of heat is released when 5.00 moles of NaCl form from its elements in their standard states.

asked Jan 23 in ThermoChemistry by ArmandoDaws6 (490 points)

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Calculate the heat of crystallization of 5 moles of calcium chloride, given that the enthalpy change of hydration of calcium ions is –1622 kJ/mol and that of chloride ions is –364 kJ/mol.

asked Jan 23 in ThermoChemistry by MichealY7971 (410 points)

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1 answer 62 views

Calculate the heat of crystallization of 10 grams of sodium acetate trihydrate (NaC2H3O2•3H2O) when it is cooled from 50°C to 10°C and crystallizes. The specific heat capacity of water is 4.18 J/g°C. The molar mass of sodium acetate is 82.03 g/mol.

asked Jan 23 in ThermoChemistry by RickHain0181 (490 points)

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1 answer 53 views

Calculate the heat of crystallization in kJ/mol of a substance, given that 100 g of it dissolved in water and cooled from 60°C to 20°C, releasing 5490 J of heat. The molar mass of the substance is 120 g/mol.

asked Jan 23 in ThermoChemistry by Britt76E056 (410 points)

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1 answer 42 views

Calculate the heat of crystallization for the solidification of 25 grams of a solution containing 10% sucrose (C12H22O11) by mass. The enthalpy of solution for sucrose in water at a given temperature is -5.73 kJ/mol. The molar mass of sucrose is 342.3 g/mol. Assuming that the solution completely solidifies upon cooling, determine the energy released or absorbed in the process.

asked Jan 23 in ThermoChemistry by ZaneSouthwic (230 points)

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Calculate the heat of crystallization for NaCl from the given data:The enthalpy of fusion of NaCl = 28.3 kJ/mol and the heat capacity of NaCl is approximately constant at 40.0 J/mol.K for temperatures close to room temperature. The melting point of NaCl is 801 °C and the density of the solid NaCl is 2.16 g/cm³.

asked Jan 23 in ThermoChemistry by ErnestinaB30 (470 points)

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Calculate the heat of crystallization (in kJ/mol) of NaOH if 25g of NaOH dissolves in 100g of water at 25°C and releases 4.75kJ of heat.

asked Jan 23 in ThermoChemistry by GarlandGooge (230 points)

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1 answer 60 views

Calculate the heat of combustion for propane gas, C3H8(g), if 12.5 grams of propane are completely burned in excess oxygen gas and the products of reaction are cooled from 700°C to 25°C. The heat capacities of the reactants and products are as follows: C3H8(g): cp = 44.10 J/K O2(g): cp = 29.38 J/K CO2(g): cp = 36.8 J/K H2O(g): cp = 33.6 J/K Assume that the heat capacities of the products and reactants are constant over the temperature range of the reaction and that the heat lost to the surroundings is negligible.

asked Jan 23 in ThermoChemistry by Manie9252773 (410 points)

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Calculate the heat of adsorption of hydrogen gas on a platinum surface given the initial temperature of the system is 298 K and the final temperature is 330 K. The mass of the platinum surface used is 5 grams, and the amount of hydrogen adsorbed is 0.01 moles. Assume the heat capacity of the system is constant at 25 J/K.

asked Jan 23 in ThermoChemistry by JennieCrumle (230 points)

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1 answer 65 views

Calculate the heat energy required to sublime 25 grams of dry ice (CO2) at -78.5 °C, given the heat of sublimation for CO2 is 573 kJ/mol.

asked Jan 23 in ThermoChemistry by HaleyCoulsto (350 points)

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1 answer 49 views

Calculate the heat capacity of a 50g sample of water that is heated from 25°C to 45°C, given that the specific heat capacity of water is 4.184 J/g°C.

asked Jan 23 in Chemical thermodynamics by ZitaClymer5 (210 points)

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Calculate the heat capacity of a 25.0 g sample of copper, given that it was heated from 25°C to 50°C when it absorbed 209 J of heat. The specific heat capacity of copper is 0.385 J/g°C.

asked Jan 23 in Chemical thermodynamics by JulietaNesbi (330 points)

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