What is the maleic anhydride melting point?

What is the maleic anhydride melting point? Maleic anhydride is an organic compound made up of carbon, hydrogen and oxygen. It is a white solid that has a chemical formula of CH₂O₂. Maleic anhydride can be found as a naturally occurring substance in plants as well as animals. It is also one of the major components of maleic acid which it forms with water. This post shall be answering what the melting point of maleic anhydride is.

Physical properties

Maleic anhydride has a melting point of 240 degrees Celsius. When such temperatures are attained, its physical properties or chemical reactions change in a very radical way. For example, maleic anhydride reacts with water to form maleic acid. Maleic anhydride begins to dissolve in water when the temperature is raised above 91 degrees Celsius and the maximum dissolve is at 100 degrees Celsius. Once dissolved in water, it gets forms ions that are charged positively or negatively depending on how much charge it has absorbed from other ions present in the water. As water evaporates, the ions become ionic salts and move towards the ground.

Chemical reactions

Maleic anhydride is a crystalline solid at room temperature but turns into a liquid when heated. When it is melted, it forms maleic acid which has a melting point of 46 degrees Celsius. The acid form of this compound is not stable and easily dissolves in water and other liquids. However, it does react with carbon dioxide to yield carbon dioxide and water. As a result, it can be used as a dehydrating agent to remove unwanted water from different substrates like plastics, paper and many more objects that have been treated with water to produce the desired result.

Factors that affect maleic anhydride melting point

1. Temperature

The temperature of the substance is the first factor that affects its melting point. As stated earlier, femaleic anhydride melts at 240 degrees Celsius and dissolves in water to form maleic acid. Maleic acid has a melting point of 46 degrees Celsius. So, maleic acid and the melting point are directly linked to each other.

2. Pressure

Temperature plays a vital role in determining the melting point of a compound but pressure has an important role in affecting it too. While maleic anhydride melts at 240 degrees Celsius, it starts to melt as soon as it reaches a pressure between 0 and 10 atmospheres at room temperature. The transition begins at pressure levels of 0.1 atmosphere and continues to increase as the pressure goes up.

3. Number and type of atoms

The number and type of atoms present in a compound affects the melting point of such compounds. For example, maleic anhydride has two oxygen atoms bonded to one carbon atom which makes it less soluble compared to its acid form; maleic acid has four oxygen atoms bonded to one carbon atom which makes it highly soluble in water.

4. Chemical composition

Factors that affect maleic anhydride melting point. Chemical composition also has a major role to play in affecting the melting point of a compound. For example, ethylene glycol is much less soluble as compared to maleic anhydride while they have similar chemical compositions.

5. Molecular structure

The molecular structure of a compound is important in determining its physical and chemical properties. In the case of maleic anhydride, it has a chain-like structure which makes it less soluble in water compared to its acid. The acid has a more potent tetrahedral shape that makes it highly soluble in water.

6. Impurities

The presence of impurities in a compound affects the melting point. Maleic anhydride is found in nature as maleic acid. It exists as a mixture of acid and water which makes it very different from maleic anhydride itself.

7. Melting range

The melting range of a compound depends on two factors. The first one is the melting point and the other is the transition between solid and liquid. Both of these factors are determined by each other when it comes to maleic anhydride. Therefore, it can be said that the melting range of maleic anhydride equals its melting point too.

8. Reactivity

The stability of the compound also has a major role to play in determining the melting point of such compounds. For example, the stability of hydrochloric acid is high but maleic anhydride is highly unstable as compared to it.

Conclusion

So what is the maleic anhydride melting point? As maleic anhydride melts at 240 degrees Celsius, it forms maleic acid when it is dissolved in water. Maleic acid has a melting point of 46 degrees Celsius which is lower than that of maleic anhydride.