Chemistry Unit 7 Quizzes 1-3 (Monarch)

Determine the value for the following reaction. N 2 (g) + 3H 2 (g) → 2NH 3 (g)+ 22,000 cal ΔH = _____

-22 kcal

How many kilojoules are associated with the formation of 2 moles of HBr(g)?

-73

A 7.83 g sample of NaCl is dissolved in 90.00 mL of ethyl alcohol (C 2 H 3 OH) solution. Calculate the molar concentration of the solution.

1.49 M

When 112 grams of carbon monoxide are consumed according to equation 2, which of the following occurs? (atomic weights: C = 12.0 g/mol, O = 16.0 g/mol)

2.00 moles of oxygen are consumed

How many g of water are required to be mixed with 11.75 g of HgCl in order to make a 0.01 m solution? (Refer to the periodic table for atomic weights.)

5,000 G

The combustion of 1 mole of CO according to the reaction CO(g) + ½O 2 (g) CO 2 (g) + 67.6 kcal gives off how much heat?

67.6 kcal

During the reaction P 4 + 5O 2 → P 4 O 10 , 1.5 moles of product were made in seconds. What is the rate of reaction?

850 g/min

The curves represent two possible reaction paths for the decomposition of ammonia, NH 3 . One can correctly conclude from the graph that the heat of the reaction corresponds to the interval labeled:

A

Reaction rates are affected by concentration, collision geometry, and the presence of a catalyst. Which of the following statements is FALSE concerning these factors?

A reaction occurs each time particles of the reactants collide.

The activated complex is located at point:

B

The collision between reactants is most likely to produce a reaction at point:

B

The curves represent two possible reaction paths for the decomposition of ammonia, NH 3 .One can correctly conclude from the graph that the smallest activation energy shown for the decomposition of NH 3 corresponds to the interval labeled:

B

Which of the following equations represents an exothermic reaction? (Select all that apply.)

C (graphite) C (diamond) , H = - 0.45 kcal CH 4 + 2O 2 CO 2 + 2H 2 O + 212,800 cal

Which of the following reactions represents an exothermic reaction?

CH 4 + 2O 2 CO 2 + 2H 2 O + 212,800 cal

Which statements concerning this diagram are correct?

E 2 > E 1 H rxn is positive.

Changing colors is not an indication of a chemical change.

False

What is the only way an equilibrium constant will change?

If there has been a change in temperature, then the constant will change.

Consider the equation 2H 2 (g) + O 2 (g) 2H 2 O(g). H is negative. Which statement is true?

Increased pressure would increase the rate of forming water vapor.

What happens to the energy release of an exothermic reaction?

It is released to the surroundings.

The action of a catalyst can be explained in the following manner:

The catalyst makes it possible for the reaction to take place by another path that makes possible reaction at a lower energy.

The energy level necessary to enable a reaction to occur is called the activation.

True

The curves represent two possible reaction paths for the decomposition of ammonia, NH 3 . One can correctly conclude from the graph that the best explanation for the difference between (I) and (II) is that:

a catalyst was added

Which of the following changes would decrease the rate of reaction?

additional heat to an exothermic reaction

What is the common device used for measuring heat transfer for chemical reactions?

calorimeter

Which of the following does not indicate a chemical change?

crushing a solid into a powder

Ammonium hydroxide ionizes as follows: NH 4 OH(s) NH 4+ (aq) + OH - (aq). If an excess of ammonium salt, such as NH 4 Cl (which ionizes to give NH 4+ (aq) ions), is added to the equilibrium shown above, you could predict that the result will be to:

decrease the concentration of OH -

A temperature change in a reaction indicates a physical change.

false

Gas produced from a reaction is a phase change, not a chemical change.

false

The brackets used to express concentration, [ ], when making equilibrium constant calculations indicate grams per liter.

false

Two objects with the same temperature must have an equal quantity of heat.

false

Consider the equation 2NO 2 (g) N 2 O 4 (g). Using ONLY the information given by the equation, which of the following changes would increase the molar concentration at equilibrium of the product N 2 O 4 (g)?

increase in pressure

Which of the following changes would increase the molar concentration of the products in any chemical reaction at equilibrium?

increase in the molar concentration of the reactants

Which of the following reactions is not a chemical reaction?

melting an ice cube

Calorimetric studies show that the following reaction is exothermic: 2NO 2 (g) N 2 O 4 (g) + 14.1 kcal. Based on this information, which one—if any—of the following additional changes would increase the molar concentration at equilibrium of N 2 O 4 (g)?

none of the above

When the products of a reaction have more energy than the reactants:

the reaction is endothermic the H is positive

The requirement that a reversible reaction be at equilibrium is that:

the velocity for the forward reaction equals that of the reverse reaction

An equilibrium is dynamic.

true

The formation of a precipitate is an indication of a chemical change.

true

Which reaction is endothermic?

½ N 2 (g) + O 2 (g) + 8.1 kcal NO 2 (g)

Which of the following reactions is endothermic?

½N 2 (g) + O 2 (g) + 8.1 kcal NO 2 (g)