What is the standard molar enthalpy of combustion for sucrose

The standard molar enthalpy of combustion of sucrose is -2222kJ*mol.

Chemical sucrose, organic compounds, molecular weight. Colorless crystals with optical rotation but no variable rotation. Molecular formula of sucrose:

c12h22o11。Sucrose is susceptible to acid hydrolysis, which produces equal amounts of D-glucose and D-fructose. Non-reducible.

The caramel formed by fermentation can be used as a color enhancer for soy sauce.

Sucrose is the main product of photosynthesis and is widely distributed in plants, especially in sugar beets, sugar cane and fruits. Sucrose is the main form of storage, accumulation and transport of sugars in plants. The white sugar and brown sugar that are usually eaten are sucrose.

Sucrose is formed by the dehydration and condensation of one molecule of glucose and one molecule of fructose, which is easily soluble in water and difficult to dissolve in ethanol, and its sweetness is second only to fructose.

White solid with a sweet taste. Solubility: Highly soluble in water, aniline, nitrogen benzene, ethyl acetate, alcohol and water mixture. Insoluble in gasoline, petroleum, anhydrous alcohol, chloroform, carbon tetrachloride.

Solubility in water: Each gram of water can dissolve sucrose, i.e. the solubility is 210g (25).It is a highly soluble sugar.

Melting Point: 186

Calories: 17 kJ g.

Note: Reasons why the silver mirror reaction cannot occur: Sucrose (a structure that does not contain hemiacetal (ketone)) is not reducible. However, after hydrolysis, a silver mirror reaction can occur.

Starting from the definition, according to the definition of the standard molar enthalpy, it refers to the standard state, which is made up of the element.

Stable elementality. The enthalpy of reaction (i.e., heat of reaction) formed by the synthesis of 1mol of compoundThe standard molar enthalpy of combustion is defined as, in the standard state, 1mol of substance.

Burn completely. enthalpy change. Note here:

Standard molar enthalpy of formation and enthalpy of combustion are both properties of a substance, and their values are measured by chemical reactions that meet their definitions. The enthalpy of reaction (i.e., the heat of reaction in high school) is the expression of the thermal effect of a reaction. Such as:

C+2H2---CH4 The reaction satisfies the standard molar enthalpy of formation, then the heat of reaction of the reaction is numerically equal to the standard molar enthalpy of ch4. (Because it is available according to the standard molar definition of enthalpy of formation.)

The most stable element.

The standard molar enthalpy of formation is equal to zero. Now that you've seen the above, here's your question: Example:

C is burned in O2 and can produce CO2 or CoThe latter case meets the standard definition of molar enthalpy of formation, but does not meet the definition of standard molar enthalpy of combustion, which is not completely combusted, hence the reaction c+1 2

The enthalpy of reaction of O2---Co is equal to the standard molar enthalpy of formation of Co (note that it is Co), but not equal to the standard molar enthalpy of combustion of C. In the first case, the standard molar enthalpy of formation and the enthalpy of combustion are met at the same time, and the complete combustion of C+O2 --- CO2 from elemental stable elements to produce a stable product, then the heat of reaction of this reaction = CO2 standard molar enthalpy of formation = c standard molar enthalpy of combustion. In addition, the stable element in the definition of standard molar enthalpy of formation (c has a variety of allotropes, and graphite is the most stable, so the stable element of c is graphite) and the problem of standard molar enthalpy of combustion stable product, etc., should be in the book.

2222kj/*mol

Reference: Inorganic and Analytical Chemistry, 73 pages, Question 3, Zhejiang University Press.

The standard molar heat of combustion of sucrose is the release of kilojoules per mole.

Sucrose, instant sugar, a kind of disaccharide, is made of a molecule of glucose's semi-acetal difference Wang Hui hydroxyl group and a molecule of fructose's semi-acetal hydroxyl group condensed and dehydrated with each other, sucrose has a sweet taste, no gas taste, soluble in water and glycerol, slightly soluble in alcohol, the relative density is 25 degrees Celsius when the gram cubic centimeter, there is optical rotation, but there is no variable optical rotation, sucrose is almost universally found in leaves, flowers, stems, seeds and fruits in the plant world. It is especially abundant in sugarcane, sugar beet and maple sap, and sucrose has a sweet taste and is an important food and sweet condiment.

The standard heat of combustion is emitted at 25 degrees Celsius, 101 kPa, when 1 mole of pure matter is completely burned to form a stable compound.

Hello, the conversion formula for the constant volume heat of combustion (j g) and constant pressure heat of combustion (j pa) of sucrose is:

J= kcal g*p*f (p is the mass of sucrose, g) where p is the density of sucrose; f (p) is the combustion temperature of sucrose and the chain is determined.

Among them, the heat of combustion refers to the energy emitted by a substance when it is burned at a specific temperature, which is equal to the mass of the substance after combustion. Therefore, the conversion formula for the constant volume heat of combustion and the constant pressure heat of combustion of sucrose is as follows:

1+q/(1-q))*

where p is the density of sucrose, g; e is the quality of sucrose, g; f (p) is the mass of sucrose after combustion, g; q is the mass per unit volume at combustion, g.

The conversion between the constant volume heat of combustion and the constant pressure heat of combustion of sucrose can be made by the following formula:

Constant pressure heat of combustion = constant volume heat of combustion + v p where δv represents the amount of volume change of the gas in the combustion reaction and p represents the pressure of the combustion reaction and is constant.

It should be noted that the formula is only applicable to the conversion between constant volume heat of combustion and constant pressure heat of combustion. In practical application, in order to calculate and compare, the calorific value of different substances is usually expressed by the value of constant pressure combustion.

The conversion formula between the thermofiber and the thermostatic heat of combustion of sucrose is as follows:

Constant volume heat of combustion = constant pressure combustion heat disorder vertical chain + v

where δv is the volume change in liters mol. It is important to note that this formula is only applicable to the combustion heat conversion of liquid sucrose.

When burning sucrose, the conversion formula for constant volume heat of combustion and constant pressure heat of combustion is:

Constant volume heat of combustion = constant pressure heat of combustion + NCO2 - NO2) t

Among them, NCO2 and NO2 are the moles of CO2 generated and O2 consumed, respectively, and δT is the temperature change (in K) during combustion, which is the gas constant.

In the formula for converting sucrose, the ratio of CO2 produced to O2 consumed when sucrose is burned.

The conversion formula of constant volume combustion heat and constant pressure combustion heat of sugar cane and lead is as follows: constant capacity burning Huai potato heat (QR) = constant pressure heat of combustion (QP) + P*[V2-V1], where P is the pressure, and V1 and V2 are the volumes before and after the combustion, respectively.