Question

What is the half-life of a first order decomposition whose rate constant is 6.2 × 10⁻⁵ s⁻¹?

a. 3.1 hr

b. 5.7 hr

c. 4.0 hr

d. 6.2 hr

Which of the following statements concerning an electrochemical cell is true?

a. The reduction occurs at the cathode for a spontaneous reaction but at the anode for the non-spontaneous reaction

b. The salt-bridge must be present to transport extra free electrons from one half-cell to the other

c. The oxidation reaction consumes electrons

d. The cell potential of a spontaneous reaction is negative

e. The oxidation occurs at the anode

Acetylene gas can react with itself to form liquid benzene. Calculate the value of K at 298.15 K for the reaction given that ∆G^⦵_rxn = −503.3 kJ·mol⁻¹.

a. 8.04 × 10³¹

b. 1.51 × 10⁸⁸

c. 2.89 × 10⁴²

d. 6.31 × 10⁵

What is the strongest intermolecular force in a sample of BeBr₂?

a. ion-dipole forces

b. hydrogen bonds

c. London forces

d. ionic bonds

e. dipole-dipole forces

Answer 1

Fon First Onder peaction, the relation betwee rate Censleme () and half life (12):18 ! k = 0.693 thinz 0:6930.6932 =trz = 6.2x10-5 sec in Phi] Lit =11:18 tid3 seci 2 For Sponteneoy reaction Econo t - Ecell = Ecathode Eanode: o d bod Ba So For Sponteneay cell, E Ecathode must be the, and higher than Eanode. Due to this the value of Excather reduction potential, got reduction occwy at Cathode, in case of sponteneous reaction, and at the But anode reaction is always an oxidation reaction • Reduction can never happen at anode. Cathode reaction & Mht the M Anode reaction > Mht thé de la So Statement a is wrong. (b) statement is correct. Saltbriedge is used to maintain electrical neutrality within internal Circuit the (C) In case of oxidation, always substrate leaves electron. So this statement is wrong

d) AG -- N FEO For sponteneous reaction AG=tve. So y Eo should be the. So this statement is also wrong @ In case of anode reaction , always Okidaitis occurs as shown before. So this statement is i correct 37 Here AG for the reaction was given. AG=-503.3 kJ molle By defination AG ==RT in K. + RI In K = 7503.3 x 103 1.= Ink = 503.3 x103. 8.314x298.15 mus l ik = 203.680 04 = 1066* to 88 20 1.57X1600 So correct ans =(6) 151x10.88 47 Be Br is a covalent molecule. So here only intermolecular force is London forces, which arise due to instanteneous dipole moment