Description : In which of the following reactions, standard reaction entropy change (S°) is positive and standard Gibb's energy change (G°) decreases sharply with increasing temperature? (1) 2 2 1 1 1 C graphite O (g) CO (g) 2 2 2 (2) 2 1 C ... CO(g) O (g) CO (g) 2 (4) 2 1 Mg(s) O (g) MgO(s) 2
Last Answer : C graphite O (g) CO(g)
Description : Consider the following reactions at `1000^(@)C`. (A) `Zn_((s))+1/2 O_(2(g)) rarr ZnO_((s)), DeltaG^(@)=-360` kJ/mol (B) `C_("(gra)")+1/2 O_(2(g)) rarr
Last Answer : Consider the following reactions at `1000^(@)C`. (A) `Zn_((s))+1/2 O_(2(g)) rarr ZnO_((s)), DeltaG^( ... a) and (b) are true D. both (a) and (b) false
Description : Consider the following reaction at `1000^(@)C` `(A) Zn_((s))+(1)/(2)O_(2(s))+ZnO_(s),DeltaG^(0)=-360kJ"mole"^(-1)` (B) `(B) Cn_((s))+(1)/(2)O_(2(g))to
Last Answer : Consider the following reaction at `1000^(@)C` `(A) Zn_((s))+(1)/(2)O_(2(s))+ZnO_(s),DeltaG^ ... 1 and 2 are true D. Both statement 1 and 2 are false
Description : `DeltaG^(@) vsT` plot in the Ellingham diagram slopes down for the reaction.
Last Answer : `DeltaG^(@) vsT` plot in the Ellingham diagram slopes down for the reaction. A. `Mg+(1)/(2)O_(2)toMgO` B. ` ... (2)toCO` D. `CO+(1)/(2)O_(2)toCO_(2)`
Description : The Gibbs free energy change of a reaction at `27^(@)C` is -26 Kcal. and its entropy change is -60 Cals/K. `Delta H` for the reaction is :-
Last Answer : The Gibbs free energy change of a reaction at `27^(@)C` is -26 Kcal. and its entropy change is -60 Cals/K. ... Cals. C. 34 K. Cals. D. `-24` K. Cals.
Description : Pick out the wrong statement. (A) Surface tension of a substance vanishes at critical point, as there is no distinction between liquid and vapour phases at its critical point (B) Entropy of ... is negative for exothermic reactions (D) The eccentric factor for all materials is always more than one
Last Answer : (D) The eccentric factor for all materials is always more than one
Description : In conversion of lime-stone to lime, `CaCO_(3(s)) to CaO_((s)) + CO_(2(g))` the values of `DeltaH^@` and `DeltaS^@` are `+179.1 kJmol^(-1)` and `160.2
Last Answer : In conversion of lime-stone to lime, `CaCO_(3(s)) to CaO_((s)) + CO_(2(g))` the values of `DeltaH^@` and ... : A. 1008 K B. 1200 K C. 845 K D. 1118 K
Description : Assertion : Reduction of ZnO with carbon is done at `1100^(@)C`. Reason : At this temperature, `DeltaG^(@)` is negative and the process is spontaneous
Last Answer : Assertion : Reduction of ZnO with carbon is done at `1100^(@)C`. Reason : At this temperature, ... ^(@)` is negative and the process is spontaneous.
Description : For the formation of metal oxide, `deltaG^(@)` __________ with increase in temperature.
Last Answer : For the formation of metal oxide, `deltaG^(@)` __________ with increase in temperature. A. Only I B. I,II only C. I,II,III only D. All
Description : Assertion :- Entropy of system increases for a spontaneous reactions. Reason :- Enthalpy of reaction always decreases for spontaneous reaction.
Last Answer : Assertion :- Entropy of system increases for a spontaneous reactions. Reason :- Enthalpy of reaction ... D. If both Assertion & Reason are false.
Description : At the point of intersection for any two reactions for any two reactions in Ellingham diagram, the gibbs energy `(DeltaG)` changes becomes
Last Answer : At the point of intersection for any two reactions for any two reactions in Ellingham diagram, the gibbs energy `(DeltaG ... `gt1` B. 1 C. `lt0` D. 0
Description : Assertion (A): There is no reaction known for which `DeltaG` is positive, yet it is spontaneous. Reason (R ) : For photochemical reaction, `DeltaG` is
Last Answer : Assertion (A): There is no reaction known for which `DeltaG` is positive, yet it is spontaneous. ... False. D. If both Assertion & Reason are false.
Description : Calculate the entropy of `Br_(2)(g)` in the reaction `H_(2)(g)+Br_(2)(g)rarr2HBr(g), Delta S^(@)=20.1 JK^(-1)` given, entropy of `H_(2)` and HBr is 13
Last Answer : Calculate the entropy of `Br_(2)(g)` in the reaction `H_(2)(g)+Br_(2)(g)rarr2HBr(g), Delta S^(@)=20.1 JK^(-1 ... ` C. `24.63 JK^(-1)` D. `20 KJK^(-1)`
Description : Calculate the enthalpy of vaporisation per mole for ethanol. Given `DeltaS = 109.8 J K^(-1) mol^(-1)` and boiling point of ethanol is `78.5^(@)`.
Last Answer : Calculate the enthalpy of vaporisation per mole for ethanol. Given `DeltaS = 109.8 J K^(-1) mol^(-1)` ... KJ mol^(-1)` D. Some more data is required
Description : If the enthaply change for the transition of liquid water to steam is 30 KJ `"mol"^(-1)` at `27^(@)` C . The entropy change for the process would be
Last Answer : If the enthaply change for the transition of liquid water to steam is 30 KJ `"mol"^(-1)` at `27^(@)` C . The ... K^(-1)` D. `100 J mol^(-1)K^(-1)`
Description : Does Barry Gibb have children?
Last Answer : Yes, Barry Gibb has 5 kids.
Description : A reaction `A +B rarr C+D +q` is found to have a positive entropy change, the reaction will be:
Last Answer : A reaction `A +B rarr C+D +q` is found to have a positive entropy change, the ... Not possible at any temperature D. Possible at any temperature
Description : What is meant by entropy driven reaction? How can the reaction with positive change of enthalpy and entropy be made entropy driven?
Last Answer : Ans.The free energy change of a reaction is given by ΔG = ΔH - TΔS For a reaction to be spontaneous, ΔG should be -ve. If both ΔH and ΔS are positive ΔG can be -ve if TΔS>ΔH in magnitude. Thus, entropy ... is low, TΔS should be greater than ΔH (ii) If ΔS is small, T should be so large that TΔS>ΔH.
Description : What is the standard enthalpy change at 298 K for the following reaction? `CO_(2) (g)+ C("diamond") rarr 2CO(g)` Given : `DeltaH_(f)^(@)(CO,g) = - 110
Last Answer : What is the standard enthalpy change at 298 K for the following reaction? `CO_(2) (g)+ C("diamond") rarr 2CO(g ... `+172.5 kJ//mol` D. `170.5 kJ//mol`
Description : (A) The reduction reaction, `Cr_(2)O_(3)+2Al to Al_(2)O_(3)+2Cr, DeltaG^(0)=-421KJ` is not possible at room temperature (R ) Certain amount of activat
Last Answer : (A) The reduction reaction, `Cr_(2)O_(3)+2Al to Al_(2)O_(3)+2Cr, DeltaG^(0)=-421KJ` is not ... incorrect D. If (A) is incorrect but (R ) is correct
Description : For which one of the following reaction, the graph of `DeltaG` against T is almost horizontal to temperature axis
Last Answer : For which one of the following reaction, the graph of `DeltaG` against T is almost horizontal to temperature axis A. ... ((s))+O_(2(g)) to 2MgO(g)`
Description : Pick out the wrong statement. (A) Enthalpies of all elements in their standard states are assumed to be zero (B) Combustion reactions are never endothermic in nature (C) Heat of reaction ... to the change in internal energy (D) Clausius-Clapeyron equation is not applicable to melting process
Last Answer : (D) Clausius-Clapeyron equation is not applicable to melting process
Description : A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system (A) its internal energy (U) decreases and its entropy (S) increases (B) U and S both decreases (C) U decreases but S is constant (D) U is constant but S decreases
Last Answer : (B) U and S both decreases
Description : During throttling process (a) heat exchange does not take place (b) no work is done by expanding steam (c) there is no change of internal energy of steam (d) all of the above (e) entropy decreases.
Last Answer : Answer : d
Description : Standard entropy of `X_(2)` , `Y_(2)` and `XY_(3)` are `60, 40 ` and `50JK^(-1)mol^(-1)` , respectively. For the reaction, `(1)/(2)X_(2)+(3)/(2)Y_(2)r
Last Answer : Standard entropy of `X_(2)` , `Y_(2)` and `XY_(3)` are `60, 40 ` and `50JK^(-1)mol^(-1)` , respectively ... be: A. 500 K B. 750 K C. 1000 K D. 1250 K
Description : For which reaction from the following, `DeltaS` will be maximum?
Last Answer : For which reaction from the following, `DeltaS` will be maximum? A. `Ca(s)+1//2O_(2)(g)rarr CaO(s)` B. `CaCO_( ... ` D. `N_(2)(g)+O_(2)(g)rarr 2NO(g)`
Description : When ice cubes are made, the entropy of water – (1) does not change (2) decreases (3) increases (4) may either increase or decrease depending on the process used
Last Answer : (2) decreases Explanation: When water is frozen into ice, the temperature drops below 0°C. Since the entropy of the solid is less than that of the liquid, the entropy of the water (the system ... decrease is found by dividing the heat of fusion of ice by the temperature for the reversible pathway.
Description : When ice cubes are made, the entropy of water (1) does not change (2) decreases (3) increases (4) may either increase or decrease depending on the process used
Last Answer : decreases
Description : Which one of the following statements is not correct? A Since voltage depends on concentrations, using standard conditions makes it easier to compare different electrochemical reactions. B We have ... half-reactions are determined by combining the relevant half-cell with a standardised half-cell.
Last Answer : C The direction of a redox reaction can only be determined experimentally.
Description : When a salt dissolves in water (a) Entropy decreases (b) Entropy increases (c) Free energy increases (d) Heat is liberated
Last Answer : Ans:(b)
Description : For a spontaneous process, free energy (A) Is zero (B) Increases (C) Decreases whereas the entropy increases (D) And entropy both decrease
Last Answer : C) Decreases whereas the entropy increases
Description : `Delta_(f)^(@)` for `CO_(2(g)), CO_((g))` and `H_(2)O_((g))` are `-393.5,-110.5` and `-241.8kJ mol^(-1)` respectively. The standard enthalpy change `(
Last Answer : `Delta_(f)^(@)` for `CO_(2(g)), CO_((g))` and `H_(2)O_((g))` are `-393.5,-110.5` and `-241.8kJ mol^(-1 ... A. `524.1` B. `41.2` C. `-262.5` D. `-41.2`
Description : Pick out the correct statement. (A) Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero (B) Melting of ice involves increase in enthalpy and ... of an ideal gas depends only on its pressure (D) Maximum work is done under reversible conditions
Last Answer : (D) Maximum work is done under reversible conditions
Description : (A): At 1200K iron can be reduce cuprous oxide (R )L: At 1200K, `Fe+Cu_(2)O to FeO+2Cu` `DeltaG=-300kj//"mole"`
Last Answer : (A): At 1200K iron can be reduce cuprous oxide (R )L: At 1200K, `Fe+Cu_(2)O to FeO+2Cu` ` ... incorrect D. If (A) is incorrect but (R ) is correct
Description : Correct statements from the graph I) Above 1073 K,`DeltaG^(0)` for the formation of `F_(2)O_(3)` is less negative than `DeltaG^(0)` for the formation
Last Answer : Correct statements from the graph I) Above 1073 K,`DeltaG^(0)` for the formation of `F_(2)O_(3)` is less ... I B. I,II only C. I,II,III only D. All
Description : Assertion (A): May endothermic reactions that are not spontaneous at room temperature become spontaneous at high temperature. Reason (R ) : Entropy of
Last Answer : Assertion (A): May endothermic reactions that are not spontaneous at room temperature become spontaneous ... . If both Assertion & Reason are false.
Description : Which of the following reactions would result in decreased entropy?
Last Answer : N2(g) + 3H2(g) -> 2NH3(g) - Apex (Correct answer if you're taking the Unit 6 Exam)
Description : Velocity of a chemical reaction (A) Decreases with increase in temperature (B) Increases with increase of pressure of reactants for all reactions (C) Decreases with increase of reactant concentration (D) None of these
Last Answer : (D) None of these
Description : Two half-reactions of an electrochemical cell are given below : MnO-4 (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (I), E° = 1.51 V Sn2+ (aq) → Sn4+ (aq) + 2e- ... the redox equation from the standard potential of the cell and predict if the reaction is reactant favoured or product favoured. -Chemistry
Last Answer : The reactions can be represented at anode and at cathode in the following ways : At anode (oxidation) : Sn2+ → = Sn4+ (aq) + 2e- ] 5 E° = + 0.15 V At cathode (reduction) : MnO-4(aq) + 8H+ ... = E°cathode - E°anode = 1.51 - 0.15 = + 1.36 V ∴ Positive value of E°cell favours formation of product.
Description : Two half-reactions of an electrochemical cell are given below : MnO-4 (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (I), E° = 1.51 V Sn2+ (aq) → Sn4+ (aq) + ... -reactions and calculate the cell potential from the standard potentials and predict if the reaction is reactant or product favoured. -Chemistry
Last Answer : The reactions can be represented at anode and at cathode in the following ways : At anode (oxidation) : Sn2+ → Sn4+ (aq) + 2e- ] 5 E° = + 0.15 V Af cathode (reduction) : MnO-4(aq) + 8H+ ( ... = E°cathode - E°anode = 1.51 - 0.15 = + 1.36 V ∴ Positive value of E°cell favours formation of product.
Description : In which of the following cases entropy decreases?
Last Answer : In which of the following cases entropy decreases? A. Solid changing to liquid B. Expansion of a gas C. Crystals dissolve D. Polymerisation
Description : __________ decreases during adiabatic throttling of a perfect gas. (A) Entropy (B) Temperature (C) Enthalpy (D) Pressure
Last Answer : (D) Pressure
Description : Entropy of the system decreases, when (A) Snow melts into water (B) A gas expands spontaneously from high pressure to low pressure (C) Water is converted into ice (D) Both (B) & (C)
Last Answer : (D) Both (B) & (C)
Description : Pick out the wrong statement. (A) A refrigeration cycle violates the second law of thermodynamics (B) Refrigeration cycle is normally represented by a temperature vs. entropy plot (C) In a refrigerator, ... (D) One ton of refrigeration is equivalent to the rate of heat absorption equal to 3.53 kW
Last Answer : (A) A refrigeration cycle violates the second law of thermodynamics
Description : Why Entropy Decreases With Increase In Temperature?
Last Answer : ds=dQ/T. Entropy is inversely proportional to the temperature so, as temp. Increases, entropy decreases.
Description : When liquid water is converted to steam at 100˚C, the entropy of water a. increases b. decreases c. remains the same d. none of the above
Last Answer : increases
Description : The entropy __________ in an irreversible cyclic process. A. remains constant B. decreases C. increases
Last Answer : Answer: C
Description : For a reaction `2X(s)+2Y(s)rarr 2Cl(l)+D(g)` The `q_(p)` at `27^(@)C` is -28 K Cal. `mol^(-1)`. The `q_(V)` is ___________ K. Cal. `mol^(-1)` :-
Last Answer : For a reaction `2X(s)+2Y(s)rarr 2Cl(l)+D(g)` The `q_(p)` at `27^(@)C` is -28 K Cal. `mol^(-1)`. The `q_( ... . `-27.4` B. `+27.4` C. `-28.6` D. `28.6`
Description : Optically active amine having molecular formula `C_(5)H_(13)N` on reaction with `NaNO_(2)+HCI` produces, `3^(@)` optically inative alcohol. Find out s
Last Answer : Optically active amine having molecular formula `C_(5)H_(13)N` on reaction with `NaNO_(2)+HCI` produces, ` ... out structures of amines: A. B. C. D.
Description : The value of enthalpy change `(DeltaH)` for the reaction `C_(2)H_(5)OH (l)+3O_(2) (g) rarr 2CO_(2) (g) +3H_(2)O (l)` at `27^(@)C` is `-1366.5 kJ mol^(
Last Answer : The value of enthalpy change `(DeltaH)` for the reaction `C_(2)H_(5)OH (l)+3O_(2) (g) rarr 2CO_(2) (g) + ... 1369. kJ` C. `-1364.0 kJ` D. `-1361.5 kJ`