AP Chemistry

I have the following marathon problem but am unsure where to start:

A Sample consisting of 22.7g of nongaseous, unstable compound X is placed inside a metal cylinder with a radius of 8.00cm, and a piston is carefully placed on the surface of the compound so that, for all practical purposes, the distance between the bottom of the cylinder and the piston is zero. (A hole in the piston allows trapped air to escape as the piston is placed on the compound; then this hole is plugged so that nothing inside the cylinder can escape.) The piston-and-cylinder apparatus is carefully placed in 10.00 kg of water at 25.00oC. The barometric pressure is 778 torr.
When the compound spontaneously decomposes, the piston moves up, the temperature of the water reaches a maximum of 29.52oC, and then it gradually decreases as the water loses heat to the surrounding air. The distance between the piston and the bottom of the cylinder, at the maximum temperature, is 59.8 cm. Chemical analysis shows that the cylinder contains 0.300 mol carbon dioxide, 0.250 mol liquid water, 0.025 mol oxygen gas, and an undetermined amount of gaseous element A.
It is known that the enthalpy change for the decomposition of X, according to the reaction described above, is -1893 kJ/mol X. The standard enthalpies of formation for gaseous carbon dioxide and liquid water are
-393.5 kJ/mol and -286 kJ/mol, respectively. The heat capacity for water is 4.184 J/oC · g. The conversion factor between L · atm and J can be determined from the two values for the gas constant R, namely, 0.08206 L · atm/mol · K and 8.3145 J/mol · K. The vapor pressure of water at 29.5 oC is 31 torr. Assume that the heat capacity of the piston–and–cylinder apparatus is negligible and that the piston has negligible mass.
Given the preceding information, determine

A. The formula for X

B. The pressure volume work (in kJ) for the decomposition of the 22.7-g sample of X

C. The molar change in internal energy for the decomposition of X and the approximate standard enthalpy of formation for X.

  1. 👍 0
  2. 👎 0
  3. 👁 53
asked by Derek
  1. See my response above.

    1. 👍 0
    2. 👎 0
    posted by DrBob222

Respond to this Question

First Name

Your Response

Similar Questions

  1. AP Chemistry

    I have the following marathon problem but am unsure where to start: A Sample consisting of 22.7g of nongaseous, unstable compound X is placed inside a metal cylinder with a radius of 8.00cm, and a piston is carefully placed on the

    asked by Derek on October 2, 2007
  2. chemistry

    Consider the reaction between 60.0 mL of liquid ethanol (C2H5OH; density = 0.789 g/mL) and 28.0 L of O2 at 27.0°C and a pressure of 1.51 atm? I am unsure of where to start with this problem...

    asked by Rina on November 2, 2013
  3. Calculus

    I finished the first question with no problem. It was something like: Find the points at which f(x) [insert three equations for left right and in between here] is discontinuous. At each of these points, is f cont. from the right

    asked by Elisabeth on May 22, 2010
  4. PreCalculus

    I'm unsure how to even start this problem Solve for x: Arctan( -4/5 ) + Arcos (2/SQRT(5) ) = Arctan(x)

    asked by Kate on March 9, 2010
  5. statistics

    A study of 36 marathon runners showed that they could run at an average rate of 7.8 miles per hour. The sample standard deviation is 0.6. Find a point estimate of the population mean. Find the 90% confidence interval forthe mean

    asked by Anonymous on April 24, 2013
  6. math

    Maria ran in a 42 km marathon she covered the first half of the marathon from 0600 to 0715 hours and stopped and rest. She resumed running was able to cover the remaining distance from 0720 to 0935 hours. What was Maria's average

    asked by Jenibel on September 14, 2012
  7. statistics

    for the population consisting of four abservations 1,3,5,7, find the dampling distribution of the sample mean for sample size n=2

    asked by Anonymous on June 19, 2012
  8. Math

    A Marathon runner runs 10 1/2 miles in 2 hrs. What is her rate? Write an expression to represent the problem. Solve the problem.

    asked by Amy on January 11, 2017
  9. Math

    A marathon runner runs 10 1/2 miles in 2 hours. What is her rate? Write an expression to represent the problem. Solve the problem:

    asked by Amy on January 23, 2017
  10. Chemistry

    A 0.60 g sample consisting of only CaC2O4 & MgC2O4 is heated at 5000C, converting the two salts of CaCO3 and MgCO3 . The sample then weighs 0.465 g. If the sample had been heated to 9000C, where the products are CaO & MgO, what

    asked by Susan on July 27, 2014

More Similar Questions