Module 14 Flashcards
If 2 molecules want to react together to form new chemicals, what is the first thing that must happen?
They must collide so that they are close enough to exchange or transfer electrons
A chemist runs a reaction at a low temperature and the runs the same reaction again at a high temperature. Which reaction runs faster?
the reaction at higher temperature will run faster.
Explain in your own words why the rate of a chemical reaction increases with increasing reactant concentration.
the rate increases because when there is a higher concentration of reactants there are more collisions between the reactants. The faster/more the collisions the faster the chemical reaction will run.
A chemistry book lists the rate constants for 2 different reactions. The first rate constant is 0.12 1/s and the second is 34.5 1/M x s. Even though the rate equations for these reactions are not given m an astute student says that the overall order of these 2 chemical reactions must be different from each other. In addition, the student says that the second reaction is faster that the first if the concentrations of the reactants are roughly the same. Why can the student make these statements?
Because one of the constants has M in its denominator and the overall order is dependent on the units, so if the units are different so is the overall order. Also if the constant is larger the reaction should be larger too.
The order of a chemical reaction with respect to one of its reactants is 0. If you double the concentration of that reactant, what happens to the rate?
The rate will stay the same
A student is studying a chemistry book and reads that for the following reaction:
CH3Cl + NaF –> CH3F + NaCl
the rate equation is:
R =k[CH3Cl][NaF]
THe student looks at the rate equation and says that since temperature does not appear in the rate equation, the rate of this reaction is obviously not affected by temperature. Is the student correct? Why or why not?
No the student is not correct. Although temperature is not directly in the rate equation, The value for the rate constant changes with temperature thus since the rate constant is in the rate equations , and since the rate constant depends on temperature the rate must also depend on temperature.
A chemist studies 2 different reactions and finds that the activation energy for reaction 1 is significantly higher than that of reaction2. Assuming that the reactant concentrations are roughly the same in the reactions, which reactions is the fastest?
the second reaction
What do we call a chemical that increases the rate of a chemical reaction without getting used uip in the process
a catalyst
What is the main difference between a heterogeneous catalyst and a homogeneous catalyst?
A heterogeneous catalyst has a different phase than the other reactants while a homogeneous catalyst has the same phase as the other reactants.
What is the purpose of a catalytic converter in an automobile?
it speeds up the reaction that converts carbon monoxide to carbon dioxide.
a reaction rate is:
the rate of change of a product in a chemical reaction
The study of reaction kinetics:
is the study of how fast a reaction proceeds
What thing increase the chemical reaction rate and why?
Higher temp: b/c it makes the molecules move faster, increasing the chance for a collision
Increasing Concentration: b/c adds more reactant molecules (or atoms) to collide with each other.
Increasing surface area of a reactant: b/c the molecule (or atoms) can more easily mingle with the molecules (or atoms) of the other reactants.
What is the rate equation and what are all its pieces?
How do we get the overall order of the chemical reaction?
R = k[A}^x{B}^y k=constant A,B = reactants x,y= exponents of the reactants
You get the over all order by adding x and y together
Are the rate units constant?
no! the units for the rate constant vary, they depend on the exponents of the rate equation
