CHEM 121 Questions and Correct Answers/ Latest Update / Already Graded

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CHEM 121 Questions and Correct
Answers/ Latest Update / Already
Graded
Process to calculate the partial pressure of a gas in a mixture


Ans: Pgas = Xgas x Ptot




Dalton's Law




How to calculate mole fraction (Xgas) from mole percentage?


Ans: Xgas = Mole% / 100




Equation to calculate average molecular mass of a gas mixture?


Ans: Average molecular mass=


∑(Xi×Mi)/∑Xi




Process of calculating mass percent of an element in a compound

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Ans: Mass % = (mass of element in compound/ total mass of compound)

x 100




Equation to relate the density of a gas to its molar mass


Ans: D = PxMW/RT




Formula to find the mass required when considering yield in a

chemical reaction


Ans: Mass required = theoretical mass/yield




How to find the final total pressure?

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Ans: 1. convert all pressures to the same unit




2. use ideal gas law to find moles of each gas




3. calculate total volume




4. calculate final total pressure using:




Ptot = ((P1xV1)+(P2xV2)...)/Vtot




Average molecular mass calculation

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Ans: 1. Determine molar mass of each gas




2. Calculate the mole fraction of each gas




3. Multiply the mole fraction of each gas by its molar mass




4. Sum the products




root mean square (rms) velocity