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Chem 116 Exam 1
Question | Answer |
---|---|
When ions become surrounded closely by solvent molecules it is... | Solvated |
Difference between electrolytes and nonelectrolytes in ionic solution | E- conduct; NE- don't conduct |
Difference between molecular, total ionic, and net ionic equations | Molecular: all reactants and products Total ionic: all substances dissociated into ions Net ionic: eliminates spectator ions and shows actual chemical change |
When dissolved in water an acid produces ___ ions and a base produces ___ ions. | Acid: H+ Base: OH- |
Strong bases have ___ or ___ in their structure; weak bases have ____ | Strong: OH- or O2- Weak: e- pair on N |
What are the products from an acid-base reaction? | H2O + Salt |
Bronsted-Lowry theory says that in an acid-base reaction, an acid ____ a proton and a base ____ a proton. | Acid donates Base accepts |
Define titration | When a known concentration of one solution is used to determine an unknown concentration of another |
Define chemical kinetics | The study of how fast reactants change into products |
Define reaction rate | The change in the concentration of reactants (or products) as a function of time |
What are the four factors of chemical kinetics? | Concentration, physical state, presence of catalysts, and temperature |
What would be the reaction rate for the following: 2A + B --> 3C | -delta[A]/2deltat + -delta[B]/deltat = delta[C]/3deltat |
What is the general form of the rate law? | Rate = k[A]^m[B]^n |
Does the rate constant change with temperature? Does it change as the reaction proceeds? | K does change with temperature; Does not change as reaction proceeds |
How can you find the components of the rate law? | By experiment! |
What is the reaction order of Rate = k[A] | First order |
What is the reaction order of Rate = k[A]^2 | Second order |
What is the reaction order of Rate = k | Zero order |
What are the differences in the integrated rate laws for each reaction order? | First: ln Second: inverse Zero: general |
What is the time it takes for the reactant concentration to reach 1/2 its initial value defined as? | Half-life |
The half life of a ____ order reaction is independent of concentration. | First |
Define collision frequency | Collisions per unit time |
What is the activation energy? | The difference between activated state and reactants, defined in forward and reverse directions. Energy it takes to reach transition state and collide. |
Determine the number of possible collisions for the following: a. 2A + 2B b. C +6D c. 5F + 4D | a. 4 b. 6 c. 20 |
As rate increases, what does activation energy do? | Decrease |
Frequency factor (A) is dependent on what to variables? | A = pZ p: orientation probability factor Z: collision frequency |
What is a species with a partial bond that is neither reactant or product? | transition state |
Define molecularity | The number of reactant particles in the step |
What is the rate determining step? | The slow step |
Define reaction intermediate | Substance formed and used up during the reaction |
Three things a valid mechanism must do/have: | 1. elementary steps must add to overall balanced equation. 2. must be physically reasonable (generally uni- or bimolecular 3. must correlate with rate law |
True or False: Only reactants included up to and including the slow step appear in the overall rate law, nothing beyond this step. | True |
In a reaction energy diagram, what do the peaks represent? | Transition state |
Define catalyst | A substance that increases the rate of a reaction without being consumed |
Catalyst result in a(n)____ yield, form _____, and require a(n) _____ total activation energy. | Catalyst result in a(n) EQUAL yield, form FASTER, and require a LOWER total activation energy. |
What is the difference between a homogeneous and heterogeneous catalyst? | Homogeneous: exist in solution with the reaction Heterogeneous: speeds up reaction in a different phase |
What is a globular protein catalyst? | Enzyme |
What's an example of catalyst in nature? (from class) | Chlorine from CFCs speeds breakdown of O3 (Ozone depletion) |
Nonmetals are generally ____ bonded while metals are generally ____ bonded. | Nonmetal: covalent Metal: ionic |
What is the simplest whole number ratio of moles of each element in a compound? | Emperical formula |
E(a) rev = E(a) fwd + ____ | delta H (heat of reaction) |
Molarity = | Moles solvent/ Liters solution |
Molality = | Moles solvent/ Kg solute |
Difference between average, instantaneous, and initial rate | Average: total change in concentration over time Instantaneous: Rate at a particular time Initial: Instantaneous rate when reactants are mixed |
The step-wise change that individual molecules undergo during a reaction is | Mechanism |
What are individual simplest steps which show which molecules collide with what? | Elementary Reactions |
Define unimolecular | One molecule or ion collides with an under active molecule and gives products of the elementary reaction (like nucleus disentegrating and going radioactive) |
Define bimolecular | Two molecules collide and give the products of the elementary reaction |
Rate of unimolecular reaction | k[A] |
rate of bimolecular reaction | k[A]^2 k[A][B] |
Is a reversible reaction fast or slow? | Fast. Always. |
To react, must molecules collide or have energy to overcome mutual repulsion? | Both! |
If you mix 2M NaCl adn 2M HCl, what will be the molarity of the resulting concentration? | 1M; Double the volume, half the concentration |
Given the rate law, by what factor does the rate change if each of the following occurs? Rate = k[A]^2[B] 1. [A] is tripled 2. [A] and [B] are doubled 3. [B] is halved | 1. increase by 9 2. increase by 8 3. decrease by 1/2 |
*Reminder: Review question 4 from recitation 4 | Just do it |
What is the difference between the differential and integrated rate law? | Differential: rate as a function of concentration Integrated: Concentration as a function of time |
What was the purpose of the calibration plot in the Iron Equilibrium lab | to determine the concentration of the unknown |