CHEM Final units 4&5

SA general reaction written as A+ 2B -> C + 2D is studied and yields the following data: [A]0 / [B]0 / Initial ∆[C]/∆t 0.150 M / 0.150M / 8.00x10^-3 mol/L⋅S 0.150 M / 0.300 M / 1.06x10^-3 mol/L⋅S 0.300 M / 0.150 M / 3.20x10^-3 mol/L⋅S

1.60x10^-2 mol/L⋅S

The rate expression for a particular reaction is rate = k{A][B]2. If the final concentration of A is increased from 0.1M to 0.2M, and the concentration of B is increased from 0.2M to 0.3M, the initial rate will increase by which of the following factors?

18

Magnesium react with hydrochloric acid to produce hydrogen gas. An experiment was set up to determine the rate of production of the hydrogen gas by measuring its change in volume over the first 60 seconds of the reaction. Magnesium ribbon was cut into squares of 0.5cm^2 and 1.0 cm^2. The volume of hydrochloric acid acid solution and the total mass of magnesium were held constant in each trial. Which set of conditions would produce the highest rate of production of hydrogen gas?

3 M HCL, 0.5-cm^2 pieces of magnesium

SA general reaction written as A+ 2B -> C + 2D is studied and yields the following data: [A]0 / [B]0 / Initial ∆[C]/∆t 0.150 M / 0.150M / 2.00x10^-3 mol/L⋅S 0.150 M / 0.300 M / 4.00x10^-3 mol/L⋅S 0.300 M / 0.150 M / 8.00x10^-3 mol/L⋅S

4.00x10^-3 mol/L⋅S

The rate expression for a particular reaction is rate = k{A][B]2. If the final concentration of A is increased from 0.1M to 0.2M, and the concentration of B is increased from 0.2M to 0.4M, the initial rate will increase by which of the following factors?

8

2NOCl -> 2NO + Cl2 The reaction above takes place with all of the reactants and products in the gaseous phase. Which of the following is true of the relative rates of disappearance of the reactants and appearance of the products?

Cl2 appears at half the rate that NOCL disappears. or NO appears at the same rate that NOCl disappears.

5Fe2+(aq) + MnO4-(aq) + 8H+(aq) -> 5Fe+3(aq) +Mn2+(aq) + 4H2O(I) Which of the following represents the oxidation half-reaction based on the balanced ionic equation shown above?

Fe2+(aq) -> Fe3+(aq) + e-

which of the following is the net iconic equation for the reaction between aqueous sodium chloride and hydrofluoric acid?

HF(aq) -> F-(aq) + H=(aq) F-(aq) + H+(aq) -> HF(aq)

When free Cl(g) atoms encounter O3(g) molecules in the upper atmosphere, the following reaction mechanism is proposed to occur. Cl(g) + O3 -> ClO(g) + O2(g) slow step ClO(g) + O3(g) -> Cl(g) + 2O2(g) fast step Which of the following reaction energy profiles best corresponds to the proposed mechanism?

Larger first reaction (bump) smaller second (bump)

NH4+(aq) + OH-(aq) -> NH3(aq) + H2O(I) The ammonium ion, NH4+, is observed at the end of the reaction. Which of the following statements is true?

NH3(aq) is a stronger base then OH-(aq) is.

2Na2O2(s) + S(s) + 2H2O(I) -> NaOH(aq) + SO2(aq) Atoms of which element are reduced in the reaction above?

O in Na2O2; each atom gains one electron

AB2(g) + XB(g) -> AB(g) + XB2(g) The elementary steps of a proposed mechanism for the reaction above are represented below: Step 1: 2ABa(g) -> AB(g) + AB(g) (slow) Step 2: AB3(g) + XB(g) -> AB2(g) + XB2(g) (fast) Which of the following is the rate law for the overall reaction that is consistent with the proposed mechanism?

Rate= k[AB2]^2

Based on the following experimental data, what is the rate law for the hypothetical reaction given above? Experiment:[A] / [B] / initial rate of formation c 1 0.20 / 0.10 / 2.0x10^-6 2 0.20 / 0.20 / 4.0x10^-6 3 0.40 / 0.40 / 1.6x10^-5

Rate= k[A][B]

I2 + C6H8O6 -> C6H5O6 + 2I^- + 2H^+ The compound C6H8O6 reacts with I2 according to the reaction represented by the equation above. The reaction is correctly classified as which of the following types?

Redox because C is oxidized

Rate = k[NO][Br2] What is the order for the overall reaction shown above?

Second Order

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

The presence of a catalyst in path two (Path two has a less steep bump than reaction 1)

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

The temperature of the reaction mixture increases

Rate = k[NO]^2 [Br2] What is the order for the overall reaction shown above?

Third order

Step 1: NO(g) + O3(g) -> NO2(g) + O2(g) Step 2: No2(g) + O(g) -> NO(g) + O2(g) A reaction mechanism for the destruction of ozone, O3(g), is represented above. In the overall reaction, NO(g) is best described as

a catalyst

Step 1: NO(g) + O3(g) -> NO2(g) + O2(g) Step 2: No2(g) + O(g) -> NO(g) + O2(g) A reaction mechanism for the destruction of ozone, O3(g), is represented above. In the overall reaction, NO2(g) is best described as

an intermediate

The catalyzed pathway in a reaction mechanism causes a ________ reaction rate because it has a ________ activation energy.

higher, lower

The reaction: 2A + B -> C has the following proposed mechanism: Step 1: A + B <-> D (fast equilibrium) Step 2: D + B -> E Step 3: E + A -> C + B If step 2 is the slow step, determine the rate law.

rate = k[A][B]2

The rate constant (k) for a reaction is 3.6x10^-3 1/M⋅hours. The slope of which of the following graphs is correct for the reaction and could be used to confirm the value of k?

y- axis: 1/[1-131] x- axis: Time (hours)