What is combustion heat or combustion enthalpy ?

What is combustion heat or combustion enthalpy ?
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The change in enthalpy that occurs when a basic or compound substance is completely burned in oxygen at a certain temperature and 1 atm pressure is called combustion heat or combustion enthalpy. The change in enthalpy that occurs when a mole of a substance is completely burned in oxygen under the proof state is called the combustion heat or proof combustion enthalpy of that substance. It is expressed by H ° C.
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Given standard enthalpy of formation of `CO(-110 "KJ mol"^(-1))` and `CO_(2)(-394 "KJ mol"^(-1))`. The heat of combustion when one mole of graphite bu

Description : Given standard enthalpy of formation of `CO(-110 "KJ mol"^(-1))` and `CO_(2)(-394 "KJ mol"^(-1))`. The heat of combustion when one mole of graphite bu

Last Answer : Given standard enthalpy of formation of `CO(-110 "KJ mol"^(-1))` and `CO_(2)(-394 "KJ mol"^(-1))`. The heat ... B. `-284` KJ C. `-394` KJ D. `-504` KJ

The enthalpy change when ammonia gas is dissolved in water is called the heat of (A) Solution (B) Formation (C) Dilution (D) Combustion

Description : The enthalpy change when ammonia gas is dissolved in water is called the heat of (A) Solution (B) Formation (C) Dilution (D) Combustion

Last Answer : (A) Solution

In a boiler enthalpy of water supplied was 2000 kJ/kg. Enthalpy being added by fuel combustion is 3200 kJ/kg. Using first law of thermodynamics, find amount of heat supplied if steam generation rate is 10 tons per hour.

Description : In a boiler enthalpy of water supplied was 2000 kJ/kg. Enthalpy being added by fuel combustion is 3200 kJ/kg. Using first law of thermodynamics, find amount of heat supplied if steam generation rate is 10 tons per hour.

Last Answer : Heat supplied Q = m (h2-h1) …….(Steady flow energy equation for boiler) ; h2=3200 KJ/kg h1=2000 KJ/kg m = 10 Tons /hour = (10 x 1000)/3600 kg/sec = 2.77 Kg/sec Q = 2.77(3200-2000) = 3324 KJ/sec heat supplied for 10 Tons/hr steam generation

Which of the following equations corresponds to the enthalpy of combustion at `298K`?

Description : Which of the following equations corresponds to the enthalpy of combustion at `298K`?

Last Answer : Which of the following equations corresponds to the enthalpy of combustion at `298K`? A. `C_(2)H_(6)(g)+7//2O_(2 ... (2)(g)rarr 4CO_(2)(g)+6H_(2)O(l)`

The enthalpy combustion of a substance

Description : The enthalpy combustion of a substance

Last Answer : The enthalpy combustion of a substance A. Always positive B. Always negative C. Numerically equal to the heat of formation D. 1 and 3 both

The enthalpy of combustion of `H_(2)` , cyclohexene `(C_(6)H_(10))` and cyclohexane `(C_(6)H_(12))` are `-241` , `-3800` and `-3920KJ` per mol respect

Description : The enthalpy of combustion of `H_(2)` , cyclohexene `(C_(6)H_(10))` and cyclohexane `(C_(6)H_(12))` are `-241` , `-3800` and `-3920KJ` per mol respect

Last Answer : The enthalpy of combustion of `H_(2)` , cyclohexene `(C_(6)H_(10))` and cyclohexane `(C_(6)H_(12))` are `-241 ... "KJ mol"^(-1)` D. `242 "KJ mol^(-1)`

What is quenching heat or quenching enthalpy ?:?

Description : What is quenching heat or quenching enthalpy ?:?

Last Answer : amount of heat generated during the formation of 1 mol of water by diluting 1 mol H + of a given acid at a temperature of 25 ° C is called quenching heat or quenching enthalpy . The value of the propagation heat of all strong acids and strong bases is equal to - 57.34 kj .

What is the composition of the compound called heat or structure enthalpy ?

Description : What is the composition of the compound called heat or structure enthalpy ?

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Classify the following properties as extensive and intensive properties: Molar heat capacity, temperature, enthalpy and volume.

Description : Classify the following properties as extensive and intensive properties: Molar heat capacity, temperature, enthalpy and volume.

Last Answer : Ans. Extensive properties : Enthalpy and volume. Intensive properties: Molar heat capacity, temperature.

(i)State why heat changes in physical and chemical processes are indicated by enthalpy changes and not by entropy changes? (ii)What are the limitations of First Law of thermodynamics?

Description : (i)State why heat changes in physical and chemical processes are indicated by enthalpy changes and not by entropy changes? (ii)What are the limitations of First Law of thermodynamics?

Last Answer : (i) Most of the processes are carried out in an open system i.e, at constant pressure. (ii)(a) Can’t explain the feasibility of the reaction. (b)It poses no restriction on the direction of flow of heat. (c)Practically it is not possible to convert the heat energy into an equivalent amount of work.

What is combustion heat ? What is combustion heat ?

Description : What is combustion heat ? What is combustion heat ?

Last Answer : 1 The change in heat energy that occurs when 1 mole of a basic or composite substance is completely burned / burned in oxygen under air pressure is called combustion-heat of that substance .

Why is water not suitable for putting out a petrol fire? (1) The oxygen content of water is isolated by petrol and thus it helps in burning (2) Petrol is too inflammable to be extinguished by water (3) The heat required for combustion of petrol is very low (4) Water, being heavy, slips below petrol which thus remains in contact with air and burns

Description : Why is water not suitable for putting out a petrol fire? (1) The oxygen content of water is isolated by petrol and thus it helps in burning (2) Petrol is too inflammable to be extinguished by ... very low (4) Water, being heavy, slips below petrol which thus remains in contact with air and burns

Last Answer : (4) Water, being heavy, slips below petrol which thus remains in contact with air and burns Explanation: Water is not effective on petrol fire because it has higher density than ... while petrol stays afloat and keeps burning. Petrochemical fires are nearly always extinguished with chemical foam.

Why is water not suitable for putting out a petrol fire? (1) The oxygen content of water is isolated by petrol and thus it helps in burning (2) Petrol is too inflammable to be extinguished by water (3) The heat required for combustion of petrol is very low (4) Water, being heavy, slips below petrol which thus remains in contact with air and burns

Description : Why is water not suitable for putting out a petrol fire? (1) The oxygen content of water is isolated by petrol and thus it helps in burning (2) Petrol is too inflammable to be extinguished by ... very low (4) Water, being heavy, slips below petrol which thus remains in contact with air and burns

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The heat value of combustion of Gasoline is - (1) 12600 kJ/kg (2) 14600 kJ/kg (3) 39400 kJ/kg (4) 47000 kJ/kg

Description : The heat value of combustion of Gasoline is - (1) 12600 kJ/kg (2) 14600 kJ/kg (3) 39400 kJ/kg (4) 47000 kJ/kg

Last Answer : (4) 47000 kJ/kg Explanation: The calorific value of Gasoline is 47,300 kJ/kg. The calorific value of a fuel is the quantity of heat produced by its combustion - at constant pressure and under "normal" conditions (i.e. to 0°C and under a pressure of 1,013 mbar).

The heat value of combustion of Gasoline is (1) 12600 kJ/kg (2) 14600 kJ/kg (3) 39400 kJ/kg (4) 47000 kJ/kg

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Last Answer : 47000 kJ/kg

Why is water not suitable for putting out a petrol fire ? (1) The oxygen content of water is isolated by petrol and thus it helps in burning (2) Petrol is too inflammable to be extinguished by water (3) The heat required for combustion of petrol is very low (4) Water, being heavy, slips below petrol which thus remains in contact with air and burns

Description : Why is water not suitable for putting out a petrol fire ? (1) The oxygen content of water is isolated by petrol and thus it helps in burning (2) Petrol is too inflammable to be extinguished by ... very low (4) Water, being heavy, slips below petrol which thus remains in contact with air and burns 

Last Answer : Water, being heavy, slips below petrol which thus remains in contact with air and burns

Since the enthalpy of elements in their natural state is taken to be zero, the heat of formation `(Delta_(f)H)` of compounds

Description : Since the enthalpy of elements in their natural state is taken to be zero, the heat of formation `(Delta_(f)H)` of compounds

Last Answer : Since the enthalpy of elements in their natural state is taken to be zero, the heat of formation `( ... C. is zero D. May be positive or negative

Given that standard heat enthalpy of `CH_(4), C_(2)H_(4)` and `C_(3)H_(8)` are -17.9, 12.5, -24.8 Kcal/mol. The `Delta H` for `CH_(4)+C_(2)Hrarr C_(3)

Description : Given that standard heat enthalpy of `CH_(4), C_(2)H_(4)` and `C_(3)H_(8)` are -17.9, 12.5, -24.8 Kcal/mol. The `Delta H` for `CH_(4)+C_(2)Hrarr C_(3)

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Vertical lines on pressure-enthalpy chart show constant (a) pressure lines (b) temperature lines (c) total heat lines (d) entropy lines

Description : Vertical lines on pressure-enthalpy chart show constant (a) pressure lines (b) temperature lines (c) total heat lines (d) entropy lines

Last Answer : Ans: c

The coefficient of performance is the ratio of the refrigerant effect to the (a) heat of compression (b) work done by compressor (c) enthalpy increase in compressor (d) all of the above

Description : The coefficient of performance is the ratio of the refrigerant effect to the (a) heat of compression (b) work done by compressor (c) enthalpy increase in compressor (d) all of the above

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Short horizontal lines on pressure-enthalpy chart show (a) constant pressure lines (b) constant temperature lines (c) constant total heat lines (d) constant entropy lines

Description : Short horizontal lines on pressure-enthalpy chart show (a) constant pressure lines (b) constant temperature lines (c) constant total heat lines (d) constant entropy lines

Last Answer : Ans: a

The heat content of air is called the _____ of the air. a. Temperature b. Humidity c. Enthalpy d. Psychrometry e. Entropy

Description : The heat content of air is called the _____ of the air. a. Temperature b. Humidity c. Enthalpy d. Psychrometry e. Entropy

Last Answer : ANSWER : C

The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or "outgassed" adsorbent to from a definite concentration of adsorbate is called its (A) Integral heat of adsorption (B) Heat of wetting (C) Differential heat of adsorption (D) Heat of normal condensation

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Last Answer : (A) Integral heat of adsorption

The change in enthalpy, when a unit quantity of gas is absorbed by relatively large quantity of adsorbent (on which a definite concentration of the adsorbed gas already exists) is termed as the (A) Differential heat of adsorption (B) Heat of wetting (C) Integral heat of adsorption (D) None of these

Description : The change in enthalpy, when a unit quantity of gas is absorbed by relatively large quantity of adsorbent (on which a definite concentration of the adsorbed gas already exists) is termed as the (A) ... (B) Heat of wetting (C) Integral heat of adsorption (D) None of these

Last Answer : (A) Differential heat of adsorption

The efficiency of superheat Rankine cycle is higher than that of simple Rankine cycle because [GATE-2002] (a) The enthalpy of main steam is higher for superheat cycle (b) The mean temperature of heat addition is higher for superheat cycle (c) The temperature of steam in the condenser is high (d) The quality of stem in the condenser is low

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Last Answer :  (b) The mean temperature of heat addition is higher for superheat cycle  

In the reaction, C + O2 → CO2; ΔH = - 94 kcal. What is the heat content (enthalpy) of O2? (A) -94 kcal (B) > -94 kcal (C) < - 94 kcal (D) Zero

Description : In the reaction, C + O2 → CO2; ΔH = - 94 kcal. What is the heat content (enthalpy) of O2? (A) -94 kcal (B) > -94 kcal (C) < - 94 kcal (D) Zero

Last Answer : (D) Zero

The product of efficiency & heat transferred to the working fluid is? a. Net temperature change b. Net work done c. Net enthalpy change d. None of the mentioned

Description : The product of efficiency & heat transferred to the working fluid is? a. Net temperature change b. Net work done c. Net enthalpy change d. None of the mentioned

Last Answer : b. Net work done

Entropy is the measure of:  a. The internal energy of a gas  b. The heat capacity of a substance  c. Randomness or disorder  d. The change of enthalpy of a system

Description : Entropy is the measure of:  a. The internal energy of a gas  b. The heat capacity of a substance  c. Randomness or disorder  d. The change of enthalpy of a system

Last Answer : Randomness or disorder

Which of the following occurs in a reversible polytrophic process?  a. Enthalpy remains constant  b. Internal energy does not change  c. Some heat transfer occurs  d. Entropy remains constant

Description : Which of the following occurs in a reversible polytrophic process?  a. Enthalpy remains constant  b. Internal energy does not change  c. Some heat transfer occurs  d. Entropy remains constant

Last Answer : Some heat transfer occurs

Burning of Gasoline initially requires heat before it burns spontaneously. Which of the following does not give a good explanation of this phenomenon?  a. the initial heat rises the enthalpy of the reactant  b. the initial heat lowers the activation of energy of the reactants  c. the enthalpy of reactants is lower than the enthalpy of products.  d. The enthalpy of the product is lower than the enthalpy of the reactant

Description : Burning of Gasoline initially requires heat before it burns spontaneously. Which of the following does not give a good explanation of this phenomenon?  a. the initial heat rises the enthalpy of the reactant ... of products.  d. The enthalpy of the product is lower than the enthalpy of the reactant

Last Answer : the enthalpy of reactants is lower than the enthalpy of products.

What is the measure of the energy that is no longer available to perform useful work within the current environment?  a. enthalpy  b. entropy  c. internal energy  d. latent heat

Description : What is the measure of the energy that is no longer available to perform useful work within the current environment?  a. enthalpy  b. entropy  c. internal energy  d. latent heat

Last Answer : entropy

What is known as the total heat and heat content at various times in the history?  a. enthalpy  b. entropy  c. internal energy  d. latent heat

Description : What is known as the total heat and heat content at various times in the history?  a. enthalpy  b. entropy  c. internal energy  d. latent heat

Last Answer : enthalpy

Regardless of the process, the change in enthalpy firm moles of ideal gas is  a. Heat  b. Enthalpy  c. Entropy  d. Density

Description : Regardless of the process, the change in enthalpy firm moles of ideal gas is  a. Heat  b. Enthalpy  c. Entropy  d. Density

Last Answer : Heat

Sum of the internal energy of a substance and the product of pressure and volume.  a. Specific Heat  b. Specific Gravity  c. Isolated System  d. Enthalpy

Description : Sum of the internal energy of a substance and the product of pressure and volume.  a. Specific Heat  b. Specific Gravity  c. Isolated System  d. Enthalpy

Last Answer : Enthalpy

A system having a rigid boundary that energy, work and mass does not cross its boundaries  a. Specific Heat  b. Specific Gravity  c. Isolated System  d. Enthalpy

Description : A system having a rigid boundary that energy, work and mass does not cross its boundaries  a. Specific Heat  b. Specific Gravity  c. Isolated System  d. Enthalpy

Last Answer : Isolated System

Gas being heated at constant volume is undergoing the process of.  a. isometric  b. specific heat  c. enthalpy  d. isothermal

Description : Gas being heated at constant volume is undergoing the process of.  a. isometric  b. specific heat  c. enthalpy  d. isothermal

Last Answer : isometric

Composite property applicable to all fluids  a. Entropy  b. Enthalpy  c. Specific Heat  d. None of the above

Description : Composite property applicable to all fluids  a. Entropy  b. Enthalpy  c. Specific Heat  d. None of the above

Last Answer : Enthalpy

_____ is that property of a substance which remains constant if no heat enters or leaves the substance, while it does work or alters its volume, but which increases or diminishes should a small amount of heat enter or leave.  a. Entrophy  b. Enthalpy  c. Specific Heat  d. None of the above

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Last Answer : Entrophy

What predicts the approximate molar specific heat at high temperatures from the atomic weight?  A. Third law of thermodynamics  B. Law of Dulong and Petit  C. Mollier diagram  D. Pressure-enthalpy diagram

Description : What predicts the approximate molar specific heat at high temperatures from the atomic weight?  A. Third law of thermodynamics  B. Law of Dulong and Petit  C. Mollier diagram  D. Pressure-enthalpy diagram

Last Answer : Law of Dulong and Petit

The term “enthalpy” comes from Greek “enthalpen” which means ______.  A. Warm  B. Hot  C. Heat  D. Cold

Description : The term “enthalpy” comes from Greek “enthalpen” which means ______.  A. Warm  B. Hot  C. Heat  D. Cold

Last Answer : Heat

What refers to the measure of the disorder present in a given substance or system?  A. Enthalpy  B. Entropy  C. Heat capacity  D. Molar heat

Description : What refers to the measure of the disorder present in a given substance or system?  A. Enthalpy  B. Entropy  C. Heat capacity  D. Molar heat

Last Answer : Entropy

What is considered as the heat content of a system?  A. Enthalpy  B. Entropy  C. Internal heat  D. Molar heat

Description : What is considered as the heat content of a system?  A. Enthalpy  B. Entropy  C. Internal heat  D. Molar heat

Last Answer : Enthalpy

If heat be exchanged in a reversible manner, which of the following property of the working substance will change accordingly  (a) temperature  (b) enthalpy  (c) internal energy  (d) entropy  (e) all of the above.

Description : If heat be exchanged in a reversible manner, which of the following property of the working substance will change accordingly  (a) temperature  (b) enthalpy  (c) internal energy  (d) entropy  (e) all of the above.

Last Answer : Answer : d

Total heat of a substance is also known as  (a) internal energy  (b) entropy  (c) thermal capacity  (d) enthalpy  (e) thermal conductance.

Description : Total heat of a substance is also known as  (a) internal energy  (b) entropy  (c) thermal capacity  (d) enthalpy  (e) thermal conductance.

Last Answer : Answer : d

Change in enthalpy in a closed system is equal to heat transferred if the reversible process takes place at constant  (a) pressure  (b) temperature  (c) volume  (d) internal energy  (e) entropy.

Description : Change in enthalpy in a closed system is equal to heat transferred if the reversible process takes place at constant  (a) pressure  (b) temperature  (c) volume  (d) internal energy  (e) entropy.

Last Answer : Answer : a

According to first law of thermodynamics  (a) work done by a system is equal to heat transferred by the system  (b) total internal energy of a system during a process remains constant  (c) internal energy, enthalpy and entropy during a process remain constant  (d) total energy of a system remains constant

Description : According to first law of thermodynamics  (a) work done by a system is equal to heat transferred by the system  (b) total internal energy of a system during a process remains constant  ( ... , enthalpy and entropy during a process remain constant  (d) total energy of a system remains constant

Last Answer : Answer : d

Change in enthalpy of a system is the heat supplied at  (a) constant pressure  (b) constant temperature  (c) constant volume  (d) constant entropy  (e) N.T.P. condition.

Description : Change in enthalpy of a system is the heat supplied at  (a) constant pressure  (b) constant temperature  (c) constant volume  (d) constant entropy  (e) N.T.P. condition.

Last Answer : Answer : a

It is a common observation that naturally occurring processes have a particular direction associated with them. For instance, heat flows from a hot body to a colder body. The property of a system that is used to quantitatively describe this natural direction of events is called w) energy x) entropy y) enthalpy z) equilibrium

Description : It is a common observation that naturally occurring processes have a particular direction associated with them. For instance, heat flows from a hot body to a colder body. The property of a system ... this natural direction of events is called w) energy x) entropy y) enthalpy z) equilibrium 

Last Answer : ANSWER: X -- ENTROPY

Categorize point and path functions from following. (pressure, heat, internal energy, temperature, work, total enthalpy.)

Description : Categorize point and path functions from following. (pressure, heat, internal energy, temperature, work, total enthalpy.)

Last Answer : Point function-Pressure, temperature, internal energy, total enthalpy Path function-Heat, Work