Question

please help with- chem lab: Reaction Rates After Thought (1-4d) THANKS!!

REACTION RATES The After Thought 1. Cross out the incorrect statement(s) dealing with factors affecting the rate of a chemical reaction. The rate of a chemical reaction increases: - with increasing concentration of a reactant since the number of collisions increases - with decreasing temperature since the activation energy is reduced - by pulverizing a reacting solid because its exposed surface area increases - with the addition of a catalyst since this lowers the activation energy - when solid reactants are dissolved in an inert liquid because dispersing the particles gives them more opportunity to interact with each other + 0 2. Consider the flasks shown containing reactants before the reaction 0 has had a chance to occur. Assume the motion of the particles has been instantaneously stopped. a) Use the labels FAST and SLOW to label the flask with the fastest reaction rate and also the flask with the slowest reaction rate in the set shown below. b) Two trials are performed for the same amount of time. Flasks similar to the left hand flask shown above undergo reaction. One trial is carried out at 25 °C and the other at 40'C. The results are shown below. Label the flask with the appropriate temperature either 25 °C or 40 °C.

Answer 1

q1) incorrect state ment is rate of reaction increases with decreasing temperature.

q2)

a) fastest reaction is with label 3 (last one) (from left to right) because it is showing more no:of product molecules

slowest reaction is with label 2 (middle one) (from left to right) because it is showing less no:of product molecules

b) left hand side flask (first one) is at high temperature (400c) because it is having more no:of product molecules

   right hand side flask (second one) is at low temperature (250c) because it is having less no:of product molecules

q3)

q4)

a) trial 1 rate of the reaction = 27/40 = 6.75 x10^-1 ml/sec

trial 2 rate of the reaction = 80/40 = 2.0 ml/sec

  trial 3 rate of the reaction =43 /40 = 1.075ml/sec

b) collisions occur more frequently because concentration is more more no:of molecules are present

c) more energetic collisions occur because when temperature is rised more no:of molecules will get more energy

d) pieces of zinc will have more surface area than strip of zinc greater the surface area higher the rate of reaction