mmHg. Calculate the molaf 1a U A two mole sample of He diffuses through a hole i
ID: 696553 • Letter: M
Question
mmHg. Calculate the molaf 1a U A two mole sample of He diffuses through a hole in 32 sec. A two mole sample of an unknown as diffuses through the same hole in 64 sec. Determine the molar mass of the unknown gas. 16.00 g/mol 2.00 g/mol c. 4.00 g/mol d. 8.0 g/mol The temperature of a 90 mL sample of O2 is decreased from 750 K to 375 K as the applied pressure is increased from 1 atm to 4 atm. The new volume of the gas would be: 11.2 45.0 c. 0.0889 d. 781 A 425 g sample of iron (S.H. 0.449 J/g C) at 99.5 °C is dropped into a sample of water at 19.3°C. At thermal equilibrium, the temperature of the iron and water is 35.1 . Determine the heat change for the iron. . -15.3 kJ -12.3 kJ -6.70 kJ d. -3.68 kJ Given the following equation and standard enthalpies of formation, determine the , of Fe203. dHr(kl/mol) Fe-o co,--393.5 co=-110.5 a. +849.0 b. +1539 c. -256.3 -822.3 n regarding an unknown substance found in the ChemExplanation / Answer
1)
rate of effusion = k*1/sqrt(MM)
MM is molar mass
K is proportionality constant
rate(He)/rate(unknown) = 64/32 = 2
use:
rate(He)/rate(unknown) = sqrt(MM(unknown)/MM(He)))
2 = sqrt(MM(unknown)/4)
MM(unknown)/4 = 2^2
MM(unknown)/4 = 4
MM(unknown) = 16
Answer: 16.00 g/mol
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