AP Chem Final

A gas sample with a mass of 10 grams occupies 5.0 liters and exerts a pressure of 2.0 atm at a temperature of 26°C. Which of the following expressions is equal to the molecular mass of the gas?

A. (0.08)(299) g/mol

According to the information above, what is the standard reduction potential for the half reaction?

A. -1.66

When 4.00 mol each of X and Y are placed in a 1.00 L vessel and allowed to react at constant temperature according to the equation above, 6.00 mol of Z is produced. What is the value of the equilibrium constant, Kc?

A. 3

In a saturated solution of Zn(OH)₂ at 25°C the value of (OH⁻) is 2.0x10⁻⁵M. What is the value of the solubility product constant, Ksp, for Zn(OH)₂ at 25°C?

A. 4.0x10⁻¹⁸

How much heat is absorbed or released when 2.0 moles of CH₄ reacts with 2.0 mol of O₂

A. 890 kJ heat is released

Based on the following reaction, predict which stress will create a response that favour an increase of the reactants in the equilibrium system

A. Decrease in temperature

If the equilibrium constant for the reaction above is 3.7x10¹⁵, which of the following describes the standard voltage, E, and the standard free energy change, ∆G for this reaction?

A. E is positive and ∆G is negative

The equilibrium-constant expression for the reaction is

A. K=(AB₂)/(A)(B₂)

Which of the following causes an increase in the number of moles of PCl₅ present at equilibrium?

A. Only

The above materials were sealed in a flask and allowed to come to equilibrium at a certain temperature. A small quantity of O₂ was added to the flask, and the mixture allowed to return to equilibrium at the same temperature. Which of the following has increased over its original equilibrium value?

A. The quantity of NO₂ present

Which of the four acids listed in the table is hydrochloric acid?

Acid 2

A 1.0 mol sample of CO and a 1.0 mol sample of H₂ are pumped into a rigid, previously evacuated, 2.0 L reaction vessel at 483 K. Which of the following is true at equilibrium?

B. (H₂)<(CO)

The isomerization of cyclopropane to propylene is a first-order process with a half-life of 19 minutes at 500°C. The time it takes for the partial pressure of cyclopropane to decrease from 1.0 atmosphere to .125 atmosphere at 500°C is closest to

B. 57 minutes

Consider the equilibrium above. Which of the following changes will increase the concentration of Hgl₄²⁻?

B. Adding 6 M HNO₃

An equilibrium mixture of the reactant is placed in a sealed container at 150°C. The amount of the products may be increased by which of the following changes?

B. I and II

An equal number of moles of each of the reactant are sealed in a container and allowed to come to the equilibrium shown above. At equilibrium, which of the following must be true?

B. I only

From this information, correct deductions about the reaction at 25°C include which of the following?

B. II only

Which of the following changes alone would cause a decrease in the value of the Keq for the reaction represented above?

B. Increasing the temperature

Which of the following compounds would have the highest lattice energy?

B. MgCl₂

Consider the reaction represented by the equation 2X + 2Z → X₂Z₂. During a reaction in which a large excess of reactant X was present, the concentration of reactant Z was monitored over time. A plot of the natural logarithm of the concentration of Z versus time is shown in the figure to the lest. The order of the reaction with respect to the reactant Z is

B. first order

(paragraph) What will be the total equilibrium pressure of the system if the volume of the reaction vessel is reduced to 1.0 L at constant temperature?

C. 2.4 atm

(paragraphs and diagrams) Which diagram represents the first time that the system reaches an equilibrium state?

C. 3

At the same temperature, what is Kp for SO₂+½O₂<--> SO₃

C. 3.0

Letting A=black spheres and B=white spheres, the balanced equation for the reaction is

C. A+B₂↔ AB₂

Of the following species, which has the greatest concentration in a 1.0 M solution of acid 1 at equilibrium?

C. Acid 1

A 1 mol sample of zinc can reduce the greatest number of mole of which of the following ions?

C. Ag⁺

In order to increase the value of the equilibrium constant, K, which of the following changes must be made to the above equilibrium?

C. Decrease the temperature

Which substance would have the highest boiling point?

C. Ethylene glycol, because it has the most hydrogen bonding

Identify the three gases represented on the Maxwell-Boltzmann diagram above.

C. F₂ N₂ H₂

Which of the following pairs of chemical species, when combined in equalimolar amounts, results in a buffer with a pH closest to 7.5

C. HClO and ClO⁻

The following diagram represents an equilibrium mixtrue produced for a reaction of the type A+X→AX. If the volume is 1 L, then

C. K<1

Which of the following explains the effect on the equilibrium constant, Kc, when the temperature of the reaction system is increased to 650 K?

C. Kc will decrease because the reaction is exothermic

The most convenient way to measure the equilibrium constant for the system is to measure:

C. The pressure of the CO₂ gas

Which factor will affect both the value of the equilibrium constant and the position of equilibrium for the formation of calcium carbonate?

C. The pressure of the CO₂ gas

At a certain point in taime, a 1.00 L rigid reaction vessel contains 1.5 mol of PCl₃, 1.0 mol of Cl₂, and 2.5 mol of PCl₅. Which of the following describes how the measuredpressure in the reaction vessel will change and why it will change in that way as the reaction system approaches equilibrium at constant temperature?

C. The pressure will decrease because Q<Kc

Under which of the following conditions can be an endothermic reaction be thermodynamically favourable?

C. T∆S>∆H

The X atoms are black sphere, and the Y atoms are white. Is the reaction endothermic, isothermic, or exothermic?

C. exothermic

When the concentration of a substance B in the reaction above is doubled, all other factors being held constant, it is found that the rate of the reaction remains unchanged. The most probable explanation for this observation is that

C. substance B is not involved in the rate-determination step of the mechanism,, but is involved in subsequent steps

A 25 mL sample of a 1.0 M solution of acid 1 is mixed with 25 mL of .50 M NaOH. Which of the following best explains what happens to the pH of the mixture when a few drops of 1.0 M HNO₃ are added?

C. the pH of the mixture stays about the same, because the conjugate base of acid 1 reacts with the added H₃O⁺ ions

Must be true for a reaction that is spontaneous at all temperatures

C. ∆H<0, ∆S>0

Additional Cl₂ is injected into the system at equilibrium. Which of the following graphs best shows the rate of the reverse reaction as a function of time?

D. (its a graph, just trust me its D)

According to the standard reduction potentials given above, what is the standard cell potential for the reaction represented below?

D. +2.46V

Based on the following energy profile, predict whether kf>kr, kf=kr, or kf<kr, and , using the provided equation, whether the equilibrium constant for the process is grater than, equal to, or less that 1.

D. IV

Which of the following indicators is the best choice for this titration?

D. Indicator: phenothelein; pH Range of colour change 8.2-10.0

Which of the following was true for the system between time t₁ and time t₂?

D. The rates of the forward and reverse reactions were equal

Factors that affect the rate of chemical reaction includes which of the following?

E. I, II, and III

After the equilibrium represented above is established, some pure O₂ is injected into the reaction vessel at constant temperature. After equilibrium is reestablished, which of the following has a lower value compared to its value at the equilibrium?

E. The amount of SO₂ in the reaction vessel

Which of the following rate expressions agrees best with this possible mechanism?

a. Rate=k(NO)²

Which of the following most likely accounts for the difference between reaction path one and reaction path two?

d. The presence of a catalyst in path two

When solid ammonium chloride, NH₄Cl is added to water at 25°C, it dissolves and the temperature of the solution decreases. Which of the following is true for the values of d ∆H and ∆S for the dissolving processes?

A. (∆H) positive, (∆S) positive

What is the value of Kc at this temperature, if the volume is 1L?

A. 4

For which acid is the value of the acid-dissociation constant, Ka, the smallest

A. Acid 1

WHen the reaction represented by the equation is at equilibrium at 1 atm and 25°C, the ratio (thingy) can be increased by doing which of the following?

A. Decreasing the temperature

Which gas exerts the greatest pressure?

A. He

What part of the curve corresponds to the optimum buffer action for the acetic acid/acetate ion pair?

A. Point V

London dispersion forces are caused by

A. temporary dipoles created by the position of electrons around the nuclei in a molecule

A 1.00-L flask is filled with.30 mol of CH₄ and .40 mol of CO₂ and allowed to come to equilibrium. At equilibrium, there are .20 mol of CO in the flack. What is the value of the equilibrium constant, Kc, for the reaction?

B. 0.027

(diagram and paragraph) Which of the following temperatures must be true about the value of the equilibrium constant for the reaction at this temperature?

B. 0<K<1

What is the equilibrium expression for the decomposition of ammonium carbonate, (NH₄)₂CO₃, according to the following equation?

B. Kc=(NH₃)²(CO₂)(H₂O)

The data in th etable above were obtained for the reaction X + Y → Z. Which of the following is the rate law for the reaction?

B. Rate=k(Y)²

(there is a really long paragraph before this i dont want to type it out) Which of the following best explains the discrepancy

B. The two reactant particles must collide with a particular orientation in order to react.

Assuming all molecules are in the gas phase, the change in the number of molecules that accompanies the reaction, ∆n, is

C. -1

(bunch of info above) Based on the info above, which of the following is true?

C. Both mechanism 1 and mechanism 2 are consistent with the rate law

Which of the following solutions represents a reaction for which the standard entropy change is positive?

C. CaCo₃→ CaO+CO₂

Which gas has the strongest IMF?

C. NO

At 450C, 2.0 moles each of H₂, I₂ and HI are combined in a 1.0 L rigid container. the value of Kc at 450°C is 50. Which of the following will occur as the system moves toward equilibrium?

C. The total pressure will decrease

(long paragraph i'm not typing out) As the reaction progresses toward equilibrium, the rate of the forward reaction

C. decreases to become a constant nonzero rate at equilibrium

What is the rate constant, k, for this reaction?

C. k= 3.9x10⁻²³ min⁻¹

A mixture of gases contains 1.5 moles of oxygen, 3.0 moles of nitrogen, and .5 moles of water vapour. If the total pressure is 700 mm Hg, what is the partial pressure of the nitrogen gas?

D. 420 mm Hg

The stopcocks are opened. If the tubing connecting the containers have negligible volume, by what percentage will the pressure exerted by the neon gas decrease?

D. 67%

If equal volumes of the four acids at a concentration of .5 M are each titrated with a strong base, which will require the greatest volume of base to reach the equivalence point?

D. All the acids will require the same volume of base to reach the equivalence point

On the basis of the following information above a buffer with a pH =0 can best be made by using

D. H₂PO₄⁻ +HPO₄²⁻

Equal number of moles of HCl and O₂ in a closed system are allowed to reach equilibrium as represented by the equation above. Which of the following must be true at equilibrium?

D. II and III only

Analysis of the equilibrium constant shows that it contains 4.00 atm NH₃ and 1 atm N₂. What is the value of the equilibrium constant, Kp?

E. 0.50

Which of the following equilibrium constants indicated that its corresponding reaction goes nearly to completion?

E. Kc=1.0x10⁸

Which of the following processes involves the greatest increase in entropy?

E. MgSO₃→ MgO+SO₂

The Bronsted-Lowry bases in the reaction represented above are

NH₃(aq) and Cl⁻(aq)