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A chemistry student is given an unknown compound and asked to identify it using mass spectrometry. The mass spectrum of the compound shows a molecular ion peak at m/z 150, a base peak at m/z 135, and a few smaller peaks at m/z 91, 77, and 65. What is the possible molecular formula of the unknown compound?

asked Jan 22 in Analytical Chemistry by Lavonda96B02 (2.3k points)

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Calculate the Gibbs free energy change at 298 K for the reaction of hydrogen gas (H2) and chlorine gas (Cl2) to form hydrogen chloride gas (2HCl), given the following thermodynamic data:∆H°f (HCl) = -92.31 kJ/mol∆H°f (H2) = 0 kJ/mol∆H°f (Cl2) = 0 kJ/mol∆S°f (HCl) = -181.6 J/(mol*K)∆S°f (H2) = 130.7 J/(mol*K)∆S°f (Cl2) = 223.1 J/(mol*K)Also, determine whether the reaction is spontaneous at 298 K and if it will shift towards products or reactants.

asked Jan 23 in Chemical thermodynamics by JeanetteOffi (1.7k points)

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Calculate the amount of heat released when 50 grams of NaOH is dissolved in 500 mL of water at 25°C. The heat of crystallization of NaOH is -44.51 kJ/mol. Assume the final temperature of the solution is 25°C and the heat capacity of the solution is 4.18 J/g °C.

asked Jan 23 in ThermoChemistry by RenaBrower51 (1.7k points)

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Calculate the amount of heat energy released when 50 mL of 1 M hydrochloric acid (HCl) is mixed with 50 mL of 1 M sodium hydroxide (NaOH) solution. The heat of neutralization for the reaction between HCl and NaOH is -57.1 kJ/mol.

asked Jan 23 in ThermoChemistry by AbbeyBisson8 (1.9k points)

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1 answer 87 views

A chemistry student needs to calculate the heat required to raise the temperature of 25.0 g of water from 25°C to 60°C, given that the specific heat capacity of water is 4.18 J/g°C.

asked Jan 22 in ThermoChemistry by HalinaAlderm (1.9k points)

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1 answer 83 views

A chemistry student wants to determine the amount of iron present in a sample of orange juice. The student takes a 50 mL sample of orange juice and reacts it with excess potassium dichromate in acidic solution. After the reaction, the remaining potassium dichromate requires 12.75 mL of a 0.015 M ferrous ammonium sulfate solution to complete the reaction. What is the mass of iron present in the sample of orange juice?

asked Jan 22 in Analytical Chemistry by SantoSutclif (1.4k points)

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A chemistry student needs to calculate the enthalpy of adsorption of ammonia that is adsorbed on silica gel at a temperature of 298 K. The student is provided with the following information: - The partial pressure of ammonia in the gas phase is 0.5 atm- The initial temperature of the clean silica gel is 298 K- The final temperature of the adsorbed ammonia and silica gel mixture is 306 K- The mass of ammonia adsorbed on silica gel is 0.025 grams What is the enthalpy of adsorption of ammonia on silica gel at 298 K, in kJ/mol?

asked Jan 22 in ThermoChemistry by BuckY7205505 (1.7k points)

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1 answer 45 views

Calculate the enthalpy change for the combustion of 1 mole of methane gas (CH4) at standard conditions (25°C and 1 atm), given that the standard enthalpy of formation of methane is -74.87 kJ/mol and the standard enthalpy of formation of carbon dioxide (CO2) and water (H2O) are -393.51 kJ/mol and -285.83 kJ/mol, respectively.

asked Jan 23 in ThermoChemistry by LorenzaOrell (2.1k points)

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1 answer 93 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 CorneliusChi (1.6k points)

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1 answer 74 views

Assuming a standard hydrogen electrode is used as the reference electrode and a copper electrode is used as the working electrode in an electrochemical cell, calculate the polarization potential when the current density on the copper electrode is 0.5 mA/cm^2 and the concentration of Cu2+ in the solution is 0.1 M.

asked Jan 22 in ElectroChemistry by MelbaTulloch (2.2k points)

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1 answer 78 views

Determine the solubility of potassium nitrate (KNO3) in water at 25°C, given that its Ksp value is 74.55 g/L.

asked Jan 21 in Inorganic Chemistry by IvyHogan8844 (1.6k points)

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1 answer 82 views

A chemistry student wants to know the specific heat capacity of aluminum. The student has an aluminum block weighing 100 grams at a temperature of 20°C. The student heats the block until its temperature reaches 90°C by adding 500 Joules of heat. What is the specific heat capacity of aluminum?

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

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A chemistry student needs to determine the enthalpy change for the reaction of nitrogen gas reacting with hydrogen gas to form ammonia gas, given that they have the following information:N2(g) + 3H2(g) --> 2NH3(g) ΔH1 = -92.4 kJ/mol2H2(g) + O2(g) --> 2H2O(l) ΔH2 = -572.0 kJ/molN2(g) + O2(g) --> 2NO(g) ΔH3 = +180.6 kJ/molUse Hess's law to calculate the enthalpy change for the reaction:2NH3(g) + 5O2(g) --> 2HNO3(aq) + 2H2O(l)

asked Jan 22 in Chemical reactions by YvetteLink0 (2.0k points)

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1 answer 78 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 49 views

Calculate the amount of heat required to melt 50 grams of ice at 0 C, taking the enthalpy of fusion to be 6.01 kJ/mol.

asked Jan 23 in ThermoChemistry by BrodieUus47 (1.7k points)

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1 answer 46 views

Calculate the cell potential for the following electrochemical reaction: Cu(s) + 2 Ag+(aq) → Cu2+(aq) + 2 Ag(s) The standard reduction potentials are: Cu2+(aq) + 2 e- → Cu(s) E° = 0.34 V Ag+(aq) + e- → Ag(s) E° = 0.80 V

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

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1 answer 78 views

A student needs to analyze an unknown sample to determine the percent composition of three compounds present in it. The student conducts a combustion reaction to determine the percent of carbon and hydrogen in the sample. The remaining residue is then dissolved in water and the solution is titrated with a standardized silver nitrate solution to determine the chloride ion concentration in the sample. Calculate the percent composition of each compound in the unknown sample using mass balance calculations.

asked Jan 22 in Analytical Chemistry by ErmelindaSey (1.8k points)

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1 answer 79 views

A solution containing 0.1 M acetic acid and 0.1 M sodium acetate has a pH of 4.5. If 0.02 moles of hydrochloric acid is added to the solution, what will be the pH of the solution after equilibrium is reached? (Given pKa of acetic acid = 4.76)

asked Jan 22 in Chemical equilibrium by RoderickKyle (2.4k points)

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1 answer 82 views

A chemistry student wants to create a chemical reaction that produces exactly 25 grams of water. How many grams of hydrogen and oxygen would need to react to create this amount of water?

asked Jan 22 in Chemical reactions by MarilynnAnth (1.7k points)

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1 answer 120 views

What is the product formed when tertiary butyl alcohol undergoes dehydration in the presence of concentrated sulfuric acid?

asked Jan 21 in Organic Chemistry by StephanieLeF (1.9k points)

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