Chem

2 SO2(g) + O2(g) → 2 SO3(g) A mixture of gases containing 0.20 mol of SO2 and 0.20 mol of O2 in a 4.0 L flask reacts to form SO3. If the temperature is 25ºC, what is the pressure in the flask after reaction is complete?

((.3)(.082)(298) / (4)

. . . LiHCO3(aq) + . . . H2SO4(aq) → . . . Li2SO4(aq) + . . . H2O(l) + . . . CO2(g) When the equation above is balanced and the coefficients are reduced to lowest whole-number terms, what is the coefficient of H2O(l) ?

2

Al(s)→Al3+(aq)+3e− Zn2+(aq)+2e−→Zn(s) The half-reactions for the oxidation-reduction reaction between Al(s) and Zn2+(aq) are represented above. Based on the half-reactions, what is the coefficient for Al(s) if the equation for the oxidation-reduction reaction is balanced with the smallest whole-number coefficients?

2

The diagram above represents H2 and N2 in a closed container. Which of the following diagrams would represent the results if the reaction below were to proceed as far as possible N2+3H2 -> 2NH3

2 N2 together and 2 H3N

Ni(s)→Ni2+(aq)+2e− Ag+(aq)+e−→Ag(s) Which of the following is the balanced net ionic equation for an oxidation-reduction reaction between Ag+(aq) based on the half-reactions represented above?

2Ag+(aq)+Ni(s)→2Ag(s)+Ni2+(aq)

At 27*C, 5 identical rigid 2L vessels are filled with N2 and sealed. 4 of the 5 vessels Al's contain a .05 mol sample of NaHCO3, NaBr, Cu, or I2, as shown in the diagram above. The volume taken up by the solids is negligible and the initial pressure of N2 in each vessel is 720mm Hg. All 4 vessels;s are heated to 127*C and allowed to reach a constant pressure. At 127*C, the pressure in vessel 1 is found to be higher than that in 2. Which accounts for this observation.

2NaHCO3 -> Na2CO3 + CO2 + H2O

Which of the following particle diagrams best represents the products when four molecules of H2O2 decompose into water and oxygen at room temp

2O2 and 4 H2O

_C3H8 + _O2 -> _H2O + _CO2 When the equation for the reaction represented above is balanced and all coefficients are reduced to the lowest whole-number terms, the coefficient for O2 is

5

A particle view of a sample of H2O2(aq) is shown above. The H2O2(aq) is titrated with KMnO4(aq), as represented by the equation below. 2 MnO4−(aq) + 5 H2O2(aq) + 6 H+(aq) → 2 Mn2+(aq) + 5 O2(g) + 8 H2O(l) Which of the following particle views best represents the mixture when the titration is halfway to the equivalence point? (H2O molecules and H+ ions are not shown.)

5H2O2 and 2 Mn2+

Which of the following particulate diagrams best shows the formation of water vapor from hydrogen gas and oxygen gas in a rigid container at 125oC?

6 oxygen and 12 hydrogen atoms on both sides

A student was studying physical and chemical changes. The student carried out some procedures in the laboratory and recorded observations. For one of the procedures, the student concluded that a physical change took place, but not a chemical change. Which of the following could have been the results of the procedure?

A cube of metal was changed into a flat sheet of metal.

A student titrates 10mL samples of 1.0M solutions of each of the haloacetic acids with a standard solution of NaOH Which of the following statements correctly predicts the volume of NaOH(aq) needed to reach the equivalence point?

All of the acids will need the same volume of NaOH(aq) to reach the equivalence point.

A sample of a compound that contains only the elements C, H, and N is completely burned in O2 to produce 44.0 g of CO2, 45.0 g of H2O, and some NO2 . A possible empirical formula of the compound is

CH5N

HCl(aq)+H2O(l)→H3O+(aq)+Cl−(aq) For the dissolution of HCl in water represented above, which of the following pairs includes the Brønsted-Lowry bases?

H2O and Cl-

Potassium hydrogen phthalate, KHP, is used as a primary standard for determining the concentration of a solution of NaOH by titration. If the KHP has not been dried before weighing, the calculated molarity of the NaOH would be

Higher than the actual value, since water is included in the apparent mass of KHP

Which of the following describes the changes in forces of attraction that occur as H2O changes phase from liquid to vapor

Hydrogen bonds between H2O molecules are broken.

The table above summarizes data given to a student to evaluate the type of change that took place when substance X X was mixed with water. The student claimed that the data did not provide enough evidence to determine whether a chemical or physical change took place and that additional tests were needed. Which of the following identifies the best way to gather evidence to support the type of change that occurred when water and X X were mixed?

Measuring electrical conductivities of x and the mixture of water and X

Which of the following is the conjugate acid of NH2- ?

NH3

Cu(s)+2AgNO3(aq)→Cu(NO3)2(aq)+2Ag(s) The reaction between solid copper and aqueous silver nitrate produces solid silver and a blue solution, as represented by the balanced equation shown above. Based on the balanced equation, which of the following identifies the oxidation and reduction half-reactions?

Oxidation half-reaction Cu(s)→Cu2+(aq)+2e− Reduction half-reaction Ag+(aq)+e−→Ag(s

Equal volumes of .2M solutions of lead (II) nitrate and potassium bromide are combined to form lead(II)Bromide as a yellow precipitate. Which of the following is the correct net ionic equation for the reaction?

Pb^2+ (aq) + 2Br^_ (aq) -> PbBr2(s)

2F2(g)+2NaOH(aq)→OF2(g)+2NaF(aq)+H2O(l) A 2mol sample of F2(g) reacts with excess NaOH(aq) according to the equation above. If the reaction is repeated with excess NaOH(aq) but with 1 mol of F2(g), which of the following is correct?

The amount of OF2 produced is halved

A student places a sample of a pure metal in a crucible and heats it strongly in air. Data from the experiment are given in the table above. The final mass was determined after the sample was cooled to room temperature. Which of the following statements related to the experiment is correct?

The mass of the sample increased, so a chemical change occurred when bonds formed between the metal and another substance.

H2Se(g) + 4 O2F2(g) → SeF6(g) + 2 HF(g) + 4 O2(g) Which of the following is true regarding the reaction represented above?

The oxidation number of Se changes from -2 to +6.

A student was asked to formulate a hypothesis about what would happen if 100mL of .1M NaOH(aq) at 25* C was combined with 100mL of .1MgCl2(aq) at 25*C. Which of the follow hypotheses indicate that the student thought a chemical change would occur

The resulting solution would contain a precipitate

HCl(aq) + NaOH(aq) -> NaCl(aq) + H2O(l) a student had two dilute, colorless solutions, HCl(aq) and NaOH(aq), which were at the same temperature. The student combined the solutions, and the reaction above occurred. Which of the following results would be evidence that a chemical reaction took place?

The temperature of the reaction mixture increases

The diagrams above represent solutes present in two different dilute aqueous solutions before they were mixed. Water molecules are not shown. When the solutions were combined, a precipitation reaction took place. Which of the diagrams below is the best particle representation of the mixture after the precipitation reaction occurred?

precipitate in the bottom, no3 and na floating