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What is the purity of a sample of aspirin if its melting point is 134.5°C, compared to the literature value of 136°C? Calculate the percentage purity of the sample using the melting point range and known literature values.

asked Mar 1 in Analytical Chemistry by TheScientist (138k points)

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How can we design a system using chemical principles to efficiently recover valuable metals such as gold, silver, and platinum from electronic waste without causing harm to the environment?

asked Mar 1 in Chemical engineering by TheScientist (138k points)

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What is the reaction quotient (Q) for the following reaction at 298K, if the partial pressures of reactants and products are as follows:2NO2(g) ⇌ 2NO(g) + O2(g)[NO2] = 0.5 atm, [NO] = 0.3 atm, and [O2] = 0.7 atm.

asked Mar 1 in Chemical thermodynamics by TheScientist (138k points)

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What is the enthalpy change of dissolving 10 grams of sodium chloride (NaCl) in 100 ml of water, given that the final temperature of the solution is 25°C and the initial temperature of the water was 20°C?

asked Mar 1 in ThermoChemistry by TheScientist (138k points)

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What is the amount of heat generated in the complete combustion of 1 mole of methane gas (CH4) at constant pressure, assuming the standard enthalpy of formation of CH4 is -74.8 kJ/mol and the standard enthalpy of formation of CO2 is -393.5 kJ/mol?

asked Mar 1 in ThermoChemistry by TheScientist (138k points)

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How does the concentration and acidity of rainwater in your local area compare to the average levels reported in areas affected by acid rain, and what are the potential impacts on the environment?

asked Mar 1 in Environmental Chemistry by TheScientist (138k points)

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What is the bond length between nitrogen and oxygen atoms in NO molecule? Given the bond energy of NO is 602 kJ/mol and the reduced mass of the NO molecule is 14.8 amu.

asked Mar 1 in Chemical bonding by TheScientist (138k points)

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What is the pH of a solution with a hydrogen ion concentration of 4.2 x 10^-5 M? Use a pH meter to determine the pH of the solution and compare it to the theoretical value calculated using the Henderson-Hasselbalch equation.

asked Mar 1 in Analytical Chemistry by TheScientist (138k points)

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What is the yield of 2,4-dinitrophenol obtained in the preparation of 2,4-dinitrophenol from phenol and nitric acid, given that 10 grams of phenol was used and a 95% yield was achieved?

asked Mar 1 in Chemical synthesis by TheScientist (138k points)

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What is the theoretical basis for predicting the chemical reactivity and selectivity of a given molecule using quantum chemical calculations?

asked Feb 28 in Quantum Chemistry by TheScientist (138k points)

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What is the lattice energy of magnesium oxide (MgO) given that the ionization energy of Mg is 738 kJ/mol, the electron affinity of O is -141 kJ/mol, and the distance between the ions in MgO is 2.1 Å? Show your work and units.

asked Mar 1 in Inorganic Chemistry by TheScientist (138k points)

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What is the bond dissociation energy of the carbon-hydrogen bond in methane (CH4) when using experimental data from a combustion reaction that indicates the combustion of 1 mole of methane releases 890.4 kJ of heat?

asked Mar 1 in ThermoChemistry by TheScientist (138k points)

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What is the Gibbs free energy change (ΔG) for the reaction, given the standard Gibbs free energy change (ΔG°) and the reaction quotient (Q)? For example, for the reaction A + B → C, if ΔG° is -100 kJ/mol and Q is 0.5, what is the ΔG for the reaction?

asked Mar 1 in Chemical thermodynamics by TheScientist (138k points)

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What is the standard enthalpy of formation of methane (CH4) given the following bond dissociation energies (in kJ/mol): C-H = 413, C-C = 348, C=C = 614, C≡C = 837, H-H = 436?

asked Mar 1 in ThermoChemistry by TheScientist (138k points)

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What is the standard enthalpy change of the dissolution of 10 grams of sodium chloride in 250 milliliters of water at 25°C, given that the molar enthalpy of dissolution of sodium chloride is -3.9 kilojoules per mole?

asked Mar 1 in Chemical thermodynamics by TheScientist (138k points)

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If 2.50 moles of propane react with excess oxygen gas, how much heat is released at constant pressure if the enthalpy change of the reaction is -2044 kJ/mol?

asked Mar 1 in ThermoChemistry by TheScientist (138k points)

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The decomposition of hydrogen peroxide in aqueous solution is a first-order reaction with a rate constant of 4.6 x 10^-4 s^-1 at 25°C. Calculate the time required for 75% of a 0.010 M solution of hydrogen peroxide to decompose at 25°C.

asked Mar 1 in Chemical kinetics by TheScientist (138k points)

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How can we design and implement educational programs that better incorporate chemistry into everyday life, in order to increase students' interest in the subject and promote better understanding of the impact of chemistry on the world around us?

asked Mar 1 in Chemical education by TheScientist (138k points)

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What is the heat of sublimation of dry ice (CO2) when 60 grams of it is sublimated at a constant pressure of 1 atm? The initial temperature of dry ice is -78.5°C and its final temperature is -56.6°C.

asked Mar 1 in ThermoChemistry by TheScientist (138k points)

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What is the enthalpy of dissolution of 10 grams of sodium chloride in 100 mL of water at 25°C, given that the final solution has a concentration of 1 M? (Assume that the specific heat capacity of the solution is 4.18 J/g°C)

asked Mar 1 in ThermoChemistry by TheScientist (138k points)

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