quiz4f18key1 (1).pdf - Quiz 4 Chem 1303.001 General Chemistry Fall 2018 KEY 1(40 pts Sulfur difluoride reacts with molecular fluorine as follows SF2(g 2

# quiz4f18key1 (1).pdf - Quiz 4 Chem 1303.001 General...

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Quiz 4 Chem 1303.001 General Chemistry Fall 2018 KEY 1. (40 pts) Sulfur difluoride reacts with molecular fluorine as follows: SF 2 ( g ) + 2 F 2 ( g ) à SF 6 ( g ) a. Initially, SF 2 and F 2 are separated as shown. Calculate the number of moles of each gas present at 25.0 °C (298 K). 5.00 L at 0.500 atm 2.50 L at 1.00 atm n SF 2 = (0.500 atm)(5.00 L) = 0.102 mol n F 2 = (1.00 atm)(2.50 L) = 0.102 mol (0.0821 L•atm/mol•K)(298 K) (0.0821 L•atm/mol•K)(298 K) b. When the valve is opened, the reaction quickly goes to completion. Determine what gases remain at the end, and calculate their partial pressures. Assume the temperature remains constant at 25.0 °C (298 K). F 2 is limiting, since 0.102 moles of SF 2 requires 2 x 0.102 moles of F 2 . All of the F 2 reacts. n SF 2 = 0.102 mol F 2 1 mol SF 2 = 0.0510 mol SF 2. This is amount of SF 2 that reacts. 2 mol F 2 Amounts of gases at end of reaction: n SF 2 : (0.102 – 0.0510) mol = 0.0510 mol n SF 6 = 0.102 mol F 2 1 mol SF 6 = 0.0510 mol SF 6. This is amount of SF 6 formed. 2 mol F 2 The total volume is now (5.00 + 2.50) L = 7.50 L P SF 6 = (0.0510 mol)(0.0821 L•atm/mol•K)(298 K) = 0.166 atm (7.50 L) P SF 2 = 0.166 atm since n SF 6 = n SF 2

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• Fall '08
• Maguire
• Enthalpy, Chemical reaction, Standard enthalpy change of formation, qwater

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