Chemistry

posted by .

One proposed design for a Mars rover uses a methane gas fuel cell as its power supply. The methane fuel can be made on Mars using a chemical reaction that has been known for over 100-a the Sabatier methanation reaction:
C02(g) + 4H2(g)<--> CH4(g) +2H2O(g)
Enthalpy change is -165 KJ at 250 degrees celsius.

Predict, using Le Chatelier's Principle, the conditions required in a closed Sabatier reactor to produce the maximum amount of methane.

  • Chemistry -

    We rewrite the equation to show as much detail as we can.
    CO2 + 4H2O ==> CH4 + 2H2O + heat
    So an increase in pressure (5 moles on the left and 3 on the right) will make the shift to the side with the smaller number of moles which is to the right and we want more products; therefore, increased pressure is the way to go. Decreasing T means the reaction will try to produce more heat which means it will shift to the right and that's what we want. Finally, increasing methane and hydrogen (increasing the concn of each) makes the reaction shift to the right (adding more reactants makes the reaction try to get rid of them and it can do that by "reacting" them to form products ;-).)
    A caveat here. Decreasing T shift the reaction to the right to form more products and that is desirable; however, remember that decreasing T usually decreases the RATE of reaction; therefore, decreasing T may produce more of the products (AT EQUILIBRIUM) BUT the reaction may be so slow that a snail could move faster. Usually a compromise must be reached between the desirables versus the undesirables. For example, in the N2 + 3H2 ==> 2NH3 (the Haber process for making NH3), the commercial process use VERY high pressures (which increases the RATE and the shift) and lowers the T a little as a compensating factor but not so low that the reaction is too slow and takes a month of Sunday's to produce product. I know this probably is more than you ever wanted to know about Le Chatelier's Principle but this extra information may come in useful some day.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. chemistry

    Hydrogen gas (a potential future fuel) can be formed by the reaction of methane with water according to the following equation: CH4(g)+H2O(g) = CO(g) + 3H2(g) In a particular reaction, 26.5 L of methane gas (measured at a pressure …
  2. Chemistry

    It has been proposed that wood alcohol, CH3OH, a relatively inexpensive fuel to produce, be decomposed to produce methane. Methane is a natural gas, commonly used for heating homes. is a decomposition from wood alcohol to methane and …
  3. chemistry

    A furnace that provides heat by burning methane gas must have the correct mixture of air and fuel to operate efficiently. What is the mole ratio of air to methane gas in the combustion of methane?
  4. chemistry

    In a methane fuel cell, the chemical energy of the methane is converted into electrical energy instead of heat that would flow during the combustion of methane. Using the half-reactions and reduction potentials given below a) Write …
  5. chemistry

    In a methane fuel cell, the chemical energy of the methane is converted into electrical energy instead of heat that would flow during the combustion of methane. Using the half-reactions and reduction potentials given below a) Write …
  6. physics

    Mars Rover When the Mars rover was deployed on the surface of Mars in July 1997, radio signals took about 12 min to travel from Earth to the rover.How far was Mars from Earth at that time?
  7. Chemistry

    Natural gas is almost entirely methane, CH4. What volume of natural gas at 20 C and 1.00 atm pressure is required to heat one quart of water from 20 C to 100 C?
  8. chemistry

    Use Table 9.4 to calculate an approximate enthalpy or heat of reaction for the combustion of one mole of methane gas (CH4) to form gaseous H2O and CO2. What Volume (in L) of methane is needed to produce 3287 kJ of heat for methane …
  9. Chemistry

    Methane (CH4) is the major component of natural gas. 2.5 moles of methane were placed in a commercial colorimeter and subjected to a combustion reaction. The reaction released 2800 kJ of energy. Compare this energy value to the energy …
  10. Chemistry

    Hydrogen gas is a very environmentally friendly fuel source. One factor that is important in determining whether it is used as a fuel source is the cost of production. Use the two equations below to evaluate which reaction requires …

More Similar Questions