UUUUUUUUU 4. For an endothermic reaction: Is the energy of the products higher or lower than reactants? (circle one) b. Is heat released or absorbed c is the sign for AH positive or negative? S a. Since reactions are favorable when they release energy and form lower energy products, which reaction – (a) or (b) – is favorable? b. What is the sign (+ or -) for the energy (enthalpy) value of a favorable reaction Manager: Check to ensure that all team members aree on the answers to CTOS 33. Model 2: Molecular collisions that may result in a chemical reaction The hollow arrows indicate the direction and speed of motion of the atoms or molecules (1) A – B C 25°C * 200°C 200°C, AB 7 (3) A c B 200°C x No reaction Critical Thinking Questions: 6. When the temperature is increased: a. Do atoms and molecules move faster or slower ? (circle one) b. Do atoms and molecules have more or less kinetic energy? (circle one 7. In what way(s) are collisions between molecules at 200°C different from the collisions at room temperature (25°C)? 8. Compare reactions (1) and (2) in Model 2. In what way(s) are they different? 9. Compare reactions (2) and (3) in Model 2. In what way(s) are they different? 10. Discuss with your team, and propose at least two conditions that must be satisfied for a molecular collision to result in a chemical reaction. – 121 – CA2