AP Chem midterm review: question and answer

Based on the ionization energies of element x given in the table, which of the following is the imperial formula of an oxide element x

!!!! DOUBLE CHECK EC X2O2

X + 2Q -? R + Z k= 1.3 X105 at 50 C. A 1.0 sample of x(g) and a 1.0 mol sample of Q(g) are introduced into an evacuated rigid 10.02 cont. and allowed to reach equilibrium at 50 C according to equation above. At equilibrium, which is true:

(R) =(Z)>Q

A student mixes a 10 mL sample of 1.0 M NaOH (eq) w/ a 10 mL sample of 1.0 M HCl(aq) in a polystyreme container. the temp is 26.0 C, what is the experimental blue of change in H

-50 Kj/mol rxn

When a student adds 30.0 ml of 1.00 M HCl to .56 g of powdered Fe, a reaction occurs. when the reaction is complete at 273 K and 1.0 atom, which is true

.22 L of H2 has been produced

at 127 C the pressure in vessel 1 is found to be higher than in vessel 2. which of the following reactions best accounts for the observation

2NaHCO3-> NaCO3+C2H2

C25H30N3 + OH -> C25H30N3OH Approximately how long did it take for 75% of the initial amount of C25H30N3 to react

300 s

The student wants to use the spectrophotometer to measure with the greatest sensitivity as the reaction progresses which of the following indicates the best wavelengths selling and explains why it is best? `

590 nm, because only the violet form of the molecule will absorb significantly at this wavelength

A hot iron ball is dropped into a 200g sample of water initially at 50 C. If 8.4 KJ of heat is transferred from the ball to the water. what is the final temp of the water

60 C

N2 + 3H2 -> 2NH3 . NH3 was synthesized at 200 C in the presence of a powdered O2 catalyst heading to the equilibrium system represented above. Which of the following changes would result in more NH3 in the mixture after equilibrium is reestablished

Adding some N2(s)

Which of the following best helps explain why an increase in temperature increases the rate of a chemical reaction

At higher temperatures high energy collisions happen more frequently

the proposed mechanism can be written in a more general form as shown above. species other than Cl can also decompose O2 through the same mechanism which of the following chemical species is most likely to decompose O3 in the upper atmosphere through the above mechanism

Br

A 23.0 g sample of a compound contains 12.0 g of C, 3.0 of H3 and 8.0 of O. Which of the following is the empirical formula of the compound

C2H6O

which of the following molecules is least soluble in water

CCl4

In which of the following liquids do the intermolecular forces include dipole dipole forces?

CH2F2

On the basis of the info above, which of the following arranges the binary compounds in order of increasing bond polarity

CH4<SiCl4<SF4

Based on the information in the table above, which liquid CS2 or CCl4 has the higher equilibrium vapor pressure at 25 and why?

CS2 weaker LD forces

Which of the following correctly identifies the species associated with peak x and provides a valid justification

Ca because its nucleus has two more portions than n the nucleus of Ar has

A vessel contains Ar at high pressure. which of the following statements best helps to explain why the measured pressure calculated using the ideal gas law

D. The combined volume of the Ar atoms

Which of the following energies the molecules N2, O2, and F2 in order of their bond enthalpies from least to greatest

F2<O2<N2

The lewis electron-dot diagrams of HClO molecule and the HClO2 molecule are shown above at the left and right, respectively which of the following statements identifies a factor that contributes to its being the stronger acid

HClO3 is the stronger acid bc the additional electronegative oxygen atom on the Cl atom stabilizes the conjugate base

At room temperature I2 is a molecular solid. which of the following provides characteristic of I2 call a correct explanation>

It is not a good conductor of electricity because its valance electrons are localized in bonding and nonbonding pairs

What would be the effect on the reaction rate if the solution of C25H30N3 is diluted by a factor of 2

It would be lower

Smallest bond angle

NF3

The rate law for the reaction represented by the equatiokn above is rate = K[No2][F2]. which could be the first elementary step of a 2 step mechanism for the reaction if the 1st step is slow and the 2nd step is fast

NO2+F2 ->NO2F+F

Two trials are run, using excess water. in the first trial, 7.8 g of NO2O2 (molar mass 78g/mol) is mixed with 3.2 g of S. In the second trial, 8.8 g of NO2O2 react as completely as possible. both trials yield the same amount of SO2. which of the following identifies the limiting reactants and the heat released a, for the two trials at 258 K?

NO2O2 30 Kj

Based on columns law and the info in the table above, which of the following contains is most likely to have the weakest interaction with an adjacent water molecule in the aqueous solution

Na

Atoms of which element are reduced in the reaction?

O in NO2O2, each atom gains one electron

a sample fo CH3OH is placed in the previously evacuated vessel w a pressure of p, at 600L. What is the final pressure in the vessel after the reaction is complete and the vessel returns to 600K

P1

Which of the following is the best hypothesis regarding the oxides formed by Rb?

Rb will from RbO, RbO2, and RbO2

X(g) -> x2+e- IE = 740 Kj/mol........ FOr element X represented above, which of the following the most likely explanation for the large difference between the second and third ionization energies

The electron removed during the third ionization is, on average, much closer to the nucleus than the first two electrons removed were

at 127C, the entire sample of I2 is observed to have vaporized. how does the mass at vessel 5 at 127 compare to its mass at 27 C

The mass is the same since the number of each type....

Two samples of Mg of equal mass were placed in equal amounts of HCl containing two separate reaction vessels particle representations of the mixing of Mg and HCl in the two reaction vessels are shown in figure 1 and 2 above. water molecules are not included in the particle representations which of the reactions will initially proceed faster, and why?

The reaction in figure 2, because more Mg atoms are exposed to HCl in figure 2 than in figure 1

When reaction 3 offers, does the hybridization of the carbon atoms change?

a yes; it changes from sp to sp2

The P.E. of a system of 2 atoms as functions of intermolecular distance is shown. which is true about IMFs when internuclear distance is x?

a. attractive and repulsive forces are balanced so atomswill maintain distance x

Which of the following will most likely increase the rate of reaction represented above? C2H4 + H2 -. C2H6

adding a heterogenous catalyst to the reaction system

which of the following reaction energy profiles best corresponds to the proposed mechanism

b first bump higher than second

If equal masses the following compounds undergo complete combustion, which will yield the greatest mass of CO2?

benzene, C6H12

in paper chromatography, sample of pigment is separated into two components, x & y, as shown above. surface of paper is moderately polar. what can be concluded

d. y is more polar

In trial 2, which would be consumed more rapidly

d.y-> rate of disappearance will be double x

absorption spectrum

electron translation molecular vibration molecular rotations

Which identifies the substance that would initially present higher concentration in the distillate

ethyl acetate, bc it has a shorter carbon chain and weaker LD

based on the bond energies shown in the table, which of the following diagrams best represents the change in energy as the reaction as the reaction represented below proceeds

exothermic

A sample of a hard, solid binary compound at room temperature did not conduct electricity as a pure solid but became highly conductive when dissolved in water. which of the following types of interactions is most likely found between the particles in the substance

ionic bonds

CaCO3-> CaO + CO2 The reaction system represented above is at equilibrium. which of the following will decrease the amount of CaO in the system?

lowering the temp of system

which of the following rate laws for the overall reaction corresponds to the proposed mechanism?

rate= k[Cl][O3]

What happens to the temp in the vessel as the reaction occurs

temp must decrease because its endothermic

which statement about the bonds is most accurate

the sum of the band enthalpies of the bonds in the reactant is , the sum of the bond enthalpies of band in the products