Ap chemistry

2 MnO4-(aq) + 10 Br-(aq) + 16 H+(aq) → 2 Mn2+(aq) + 5 Br2(aq) + 8 H2O(l) How many electrons are transferred in the reaction represented by the balanced equation above?

10

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

10 HI + 2 KMnO4 + 3 H2SO4 → 5 I2 + 2 MnSO4 + K2SO4 + 8 H2O According to the balanced equation above, how many moles of HI would be necessary to produce 2.5 mol of I2, starting with 4.0 mol of KMnO4 and 3.0 mol of H2SO4 ?

5.0

Directions: Each set of lettered choices below refers to the numbered statements immediately following it. Select the one lettered choice that best fits each statement. A choice may be used once, more than once, or not at all in each set. The following questions refer to the reactions represented below. (A) H2SeO4(aq) + 2 Cl-(aq) + 2 H+(aq) → H2SeO3(aq) + Cl2(g) + H2O(l) (B) S8(s) + 8 O2(g) → 8 SO2(g) (C) 3 Br2(aq) + 6 OH-(aq) → 5 Br-(aq) + BrO3-(aq) + 3 H2O(l) (D) Ca2+(aq) + SO42-(aq) → CaSO4(s) (E) PtCl4(s) + 2 Cl-(aq) → PtCl62-(aq) A precipitation reaction

Ca2+(aq) + SO42-(aq) → CaSO4(s)

2 H2O2(aq) → 2 H2O(l) + O2(g) ΔH° = −196 kJ/molrxn The decomposition of H2O2(aq) is represented by the equation above. A student monitored the decomposition of a 1.0 L sample of H2O2(aq) at a constant temperature of 300. K and recorded the concentration of H2O2 as a function of time. The results are given in the table below. The figure shows a table with 2 columns and 5 rows. The top row contains the column labels, from left to right: column 1, Time (seconds); column 2, concentration of H 2 O 2. From top to bottom, the data is as follows: Row 2; Time, 0, concentration of H 2 O 2, 2.7. Row 3; Time, 200, concentration of H 2 O 2, 2.1. Row 4; Time, 400, concentration of H 2 O 2, 1.7. Row 5; Time, 600, concentration of H 2 O 2, 1.4. Which of the following identifies the element(s) being oxidized and reduced in the reaction?

Oxygen is both oxidized and reduced.

Equal volumes of 0.2M 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?

Pb2+(aq)+2Br−(aq)→PbBr2(s)

When a buret is rinsed before a titration, which of the techniques below is the best procedure?

Rinse the buret two times: each time with some of the titrant solution.

The following questions refer to the below. M+ is an unknown metal cation with a +1 charge. A student dissolves the chloride of the unknown metal, MCl, in enough water to make 100.0 mL of solution. The student then mixes the solution with excess AgNO3 solution, causing AgCl to precipitate. The student collects the precipitate by filtration, dries it, and records the data shown below. (The molar mass of AgCl is 143 g/mol.) text... During the course of the experiment, which of the following happens to the NO3- ions?**

They remain dissolved in the filtrate solution.

If 0.40 mol of H2 and 0.15 mol of O2 were to react as completely as possible to produce H2O, what mass of reactant would remain?

0.20 g of H2

A 0.35 g sample of Li(s) is placed in an Erlenmeyer flask containing 100 mL of water at 25°C. A balloon is placed over the mouth of the flask to collect the hydrogen gas that is generated. After all of the Li(s) has reacted with H2O(l), the solution in the flask is added to a clean, dry buret and used to titrate an aqueous solution of a monoprotic acid. The pH curve for this titration is shown in the diagram below Which of the following is the balanced net-ionic equation for the reaction between Li(s) and water?

2 Li(s) + 2 H2O(l) → 2 Li+(aq) + 2 OH−(aq) + H2(g)

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) and Ni(s) based on the half-reactions represented above?

2Ag+(aq)+Ni(s)→2Ag(s)+Ni2+(aq)**

The following questions refer to the reactions represented below. (A) H2SeO4(aq) + 2 Cl-(aq) + 2 H+(aq) → H2SeO3(aq) + Cl2(g) + H2O(l) (B) S8(s) + 8 O2(g) → 8 SO2(g) (C) 3 Br2(aq) + 6 OH-(aq) → 5 Br-(aq) + BrO3-(aq) + 3 H2O(l) (D) Ca2+(aq) + SO42-(aq) → CaSO4(s) (E) PtCl4(s) + 2 Cl-(aq) → PtCl62-(aq) A reaction in which the same reactant undergoes both oxidation and reduction

3 Br2(aq) + 6 OH-(aq) → 5 Br-(aq) + BrO3-(aq) + 3 H2O(l)

Which of the following is the net ionic equation for the reaction between aqueous sodium fluoride and hydrochloric acid?**

F−(aq)+H+(aq)→HF(aq)F−(aq)+H+(aq)→HF(aq)

Addition of sulfurous acid (a weak acid) to barium hydroxide (a strong base) results in the formation of a precipitate. The net ionic equation for this reaction is

H2SO3(aq) + Ba2+(aq) + 2 OH-(aq) ⇄ BaSO3(s) + 2 H2O(l)

Which of the following represents a process in which a species is reduced?

NO3-(aq) → NO(g)

When water is added to a mixture of Na2O2(s) and S (s) , a redox reaction occurs, as represented by the equation below. 2 N a 2 O 2 solid plus S solid plus 2 H 2 O liquid react to form 4 N a O H aqueous plus S O 2 aqueous Atoms of which element are reduced in the reaction?

O in Na2O2; each atom gains one electron

The reaction between aqueous strontium chloride (SrCl2) and aqueous potassium sulfate (K2SO4) forms a precipitate of strontium sulfate (SrSO4). Which of the following represents the net ionic equation for the reaction?

Sr2+(aq)+SO42−(aq)→SrSO4(s)