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2.83 g of a sample of haematite iron ore [iron (III) oxide, Fe2O3] were dissolved in concentrated hydrochloric acid and the solution diluted to 250 cm3. 25.0 cm3 of this solution was reduced with tin(II) chloride (which is oxidised to Sn4+ in the process) to form a solution of iron(II) ions. This solution of iron(II) ions required 26.4 cm3 of a 0.0200 mol/dm3 potassium dichromate(VI) solution for complete oxidation back to iron(III) ions.
(a) given the half–cell reactions
(i) Sn4+(aq) + 2e– ==> Sn2+(aq)
and (ii) Cr2O72–(aq) + 14H+(aq) + 6e– ==> 2Cr3+(aq) + 7H2O(l)
deduce the fully balanced redox equations for the reactions
(i) the reduction of iron(III) ions by tin(II) ions
(ii) the oxidation of iron(II) ions by the dichromate(VI) ion
(b) Calculate the percentage of iron(III) oxide in the ore.
When incomplete fuel combustion happens in automobiles, it produces carbon monoxide. How does catalysis work in getting rid of this toxic gas?
_________ is used in expressing the rate law.
a. activation energy
b. reactant concentration
c. collision theory
d. reaction time
A catalyst ______ the rate of chemical reaction without being consumed.
a. determines
b. equalizes
c. decreases
d. increases
___________ uses a catalyst that is of similar phase of the reactants and products.
a. homogeneous catalysis
b. catalytic reaction
c. heterogeneous catalysis
d. reactant concentration
Rate law reflects ___________.
a. Arrhenius equation and Integrated law
b. reaction time and reactant concentration
c. molecularity and order of reaction
d. activation energy and collision theory
Chemical kinetics is the study of ____________.
a. collision theory
b. molecularity
c. reaction rates
d. reactant concentration
Balance the reactions below using the change in oxidation number method.
- PbO2+HBr-PbBr2+O2+H2O
- PbO+NH3-Pb+N2+H2O
- KBr+KCIO2+H2SO4-Br2+KCI+K2SO4+H20
- BR^- +CIO^- +H^+ - Br2+CI^- +H20
- SN^2+ +VO4^3- +H^+-- SN^4+ +V^2+ + H20
_______ is a variable in Arrhenius equation. *
a. reactant concentration
b. order of reaction
c. reaction rate
d. temperature
___________ provides a linear equation that allows for the calculation of the concentration of a reactant at a specific time in the reaction. *
a. Chemical kinetics
b. Arrhenius equation
c. Integrated rate law
d. catalysts
Reaction rates can be explained using the concepts of collision theory and __________.
a. Arrhenius equation
b. Chemical kinetics
c. activation energy
d. progress of reaction
A reaction mechanism may occur in two or more elementary steps. The slowest among these steps is the _____________.
a. reaction intermediate step
b. overall reaction
c. rate - determining step
d. reaction rate
Reaction rates are affected by reactant concentration and _________.
a. time
b. temperature
c. collision
d. activation
Initially, a mixture of 0.200 M NO, 0.100 M H_{2} , 0.200 M H_{2}*O was permitted to reach equilibrium (initially there was no*N_{2} ). At equilibrium, the concentration of NO was discovered to be 0.062 M. Determine the value of the equilibrium constant, Ke, for the reaction:
2NO(g) + 2H_{2}(g) N_{2}(g) + 2H_{2}*O(g)
