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September 19, 2014

Homework Help: Science help

Posted by Napolian 2 on Thursday, June 21, 2012 at 3:35pm.

Will someone please check my work for me?
Molecules involved in a chemical reaction must meet to react. What is this concept called?

entropy

enthalpy

collision theory<----

reaction rate



2. Which of the following equations is used to describe reaction rates?
∆H - T∆S

S^products S^reactants

∆[reactant or product]/∆time<---

pV = nRT



3. What term refers to the difference between the energy of the transition state and the energy of the reactants?

activation energy<----

energy of entropy

energy of enthalpy

reaction rate energy



4. Which of the following factors does not increase the rate of a reaction?

increasing the concentration of the reactants

increasing the surface area of the reactants

adding an effective catalyst to the system

decreasing the temperature of the system<----



5. Adding an inhibitor to a chemical reaction will have which of the following effects on the reaction?

The inhibitor will increase the rate of the reaction.

The inhibitor will initially increase the rate of the reaction and then decrease it.

The inhibitor will decrease the rate of the reaction.<-----

The inhibitor will have no effect on the rate of the reaction.



6. What happens to a catalyst as a result of its involvement in a chemical reaction?
It is consumed.

It is not consumed.<----

It slows a chemical reaction.

It changes to something else.



7. What happens in a reaction if it is at chemical equilibrium?
The ratio of the products to reactants remains constant over time.<---

The amount of the reactant is constantly decreasing.

All of the products are used up.

There are no reactants in the system.



8. What can you calculate if you know the concentration of a reaction's products and reactants, as well as the coefficients of each in the balanced equation?

the rate of the reaction

the entropy of the reaction

the equilibrium constant<----

Gibbs free energy



9. What is the equation for the equilibrium constant for this equation?
CO + 3H2 CH4 + H2O

[CH4][H2O]/[CO][H2]3<----

[CO][H2]3/[CH4][H2O]

[CH]4[H2O]/[H2]3

[H2O][H2]/[CH4][CO]



10. What is the equilibrium expression for 2NO + Br2 2NOBr?
[NOBr]2/[NO]2[Br2]<----

[NOBr]2/[NO2][Br]2

[NO]2[Br2]/[NOBr]2

[NO2][Br]2/[NOBr2]



11. A chemical reaction is at equilibrium. What will be the effect if more of the product is added?

The reaction will shift to the left (toward the reactants).<----

There will be no effect; the reaction will stay at equilibrium.

The reaction will shift to the right (toward the products).



12. Which of the following is likely to occur if more reactants are added to a reaction that is at chemical equilibrium?

There will be no effect; the reaction will stay at equilibrium.

The reaction will shift to the left (toward the reactants).

The reaction will shift to the right (toward the products).<-----



13. Which of the following describes the effects of changes in concentration on a chemical system in equilibrium?
(Points : 3)
Gibbs free energy

Le Chtelier's principle<-----

chemical equilibrium

reaction rate



14. Changes in which of the following do not shift the equilibrium of a chemical system?

temperature

concentration

pressure

time<----



15. Consider the reaction 2NaN3 2Na + 3N2, which is the first reaction that occurs when an air bag expands in a car undergoing a collision. This reaction happens very quickly, as you might suspect. A graph showing the amount of nitrogen gas (N2) could be best described as which of the following?
The graph line's general trend is absolutely horizontal.

The graph line's general trend is increasing from left to right. <---

The graph line's general trend is decreasing from left to right.

The graph line's general trend is nearly horizontal.

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