entropy

• does entropy influence?


  the feasibility of a reaction.
• what is entropy?


  a measure of the amount of disorder in a system.
• how is entropy represented?

  an 'S' symbol.
• what are the units of entropy?


  JK-1mol-1
• what happens to entropy during a chemical reaction?

  the entropy of a system may increase or decrease.
• what must happen to entropy for a reaction to be considered feasible?

  there needs to be an increase in the disorder of the system and so an increase in the entropy.
• what is the symbol for change in entropy of a chemical reaction?

  triangle S.
• if the 'triangle S' is positive, what does this mean?

  the reaction will be feasible.
• if the 'triangle S' if negative, what does this mean?

  the reaction won't be feasible.
• what happens the more positive the 'triangle S' value is?

  the more disordered the system has become and the more feasible there reaction.
• what is the 1st factor to use to estimate the sign of 'triangle S'?

  physical state of the reactants and products.
• what are the 3 states?

  solid, liquid and gas.
• what is the particle diagram for a solid?

  this.

  
• what is the particle diagram for a liquid?

  this.

  
• what is the particle diagram for a gas?

  this.

  
• what is the particle arrangement for a solid?

  regular arrangement.
• what is the particle arrangement for a liquid?

  randomly arranged.
• what is the particle arrangement for a gas?

  randomly arranged.
• what is the particle movement for a solid?

  they vibrate in a fixed position.
• what is the particle movement for a liquid?


  they move around each other.
• what is the particle movement for a gas?

  they move quickly in all directions.
• what is the particle closeness for a solid?

  very close.
• what is the particle closeness for a liquid?

  close.
• what is the particle closeness for a gas?

  far apart.
• what are the particles in solid like?

  • fixed in a regular arrangement.
  • state of extreme low disorder.
  • the lowest entropy.
• what are the particles in liquids like?

  • more disorder than in solids as the particles can move and change positions.
  • increase in the number of ways the particles can be arranged.
  • an increase in disorder and entropy.
• what are the particles in gases like?

  • spaced far apart.
  • free to move around anywhere in the container.
  • the highest disorder and highest entropy of all 3 states.
• how can we change the physical state of a substance?

  by changing the temperature.
• what happens to entropy if there is a change of physical state occurring between the reactants and products?

  there will be a change in entropy.
• on graph of entropy against temp, what happens at point A?

  point A is the point where the particles in the solid have 0 disorder and 0 entropy.

  
• on graph of entropy against temp, what happens between A and B?

  the increase in temperature causes the kinetic energy of the particles to increase. As particles have more energy they vibrate more and entropy increases.

  
• on graph of entropy against temp, what happens between B and C?

  there is a sharp increase in entropy as the solid melts and a liquid is formed.

  
• on graph of entropy against temp, what happens between C and D?

  the continued increase in temperature causes the energy of the particles to increase further. The movement of the particles continues to increase and entropy does also.

  
• on graph of entropy against temp, what happens between D and E?

  there is a sharp increase in entropy where the liquid is boiling and turning into a gas. Gases have a much larger entropy than liquids so this increase in entropy is larger than the one between B and C.

  
• on graph of entropy against temp, what happens after E?

  after E, the entropy continues to increase as the gas particles start to spread out and become more disordered.

  
• what happens to entropy when the reactants are solid and the products include liquids or gases?

  there will be an increase in entropy so a positive value so the reaction IS feasible.
• what happens to entropy when the reactants are liquids or gases and the solids are formed?

  there will be a negative change of entropy so a negative value so the reaction ISNT feasible.