Question

What type of isomer is Maleic Acid?

Answer 1

Isomers are compounds that have the same number of atoms as each other but vary by the arrangement of the atoms. This means that isomers are compounds that have the same molecular formula but have different structural formulas.

Complete answer:
Maleic acid is also known as cis-butenedioic acid represented as $HO2CCH = CHCO2H$. Maleic acid is an unsaturated organic dibasic acid. Maleic acid has a double bond between two carboxylic acid groups. It is used in the production of polyesters for fiber-reinforced laminated mouldings and paint cars, as well as the production of fumaric acid and many other chemical materials.
Isomers are compounds that have the same molecular formula but have different structural formulas. Isomerism is classified into two main types which are Structural Isomerism and Stereoisomerism. These types are further classified into many subtypes which are Chain isomerism, Positional isomerism, Functional isomerism, Metamerism , Tautomerism and Ring-chain isomerism under Structural isomerism and Geometric isomerism and Optical isomerism under Stereoisomerism. Cis and Trans isomers are kind of Geometrical isomers.
Maleic acid is geometric isomer. Maleic acid is a diastereomer and thus a stereoisomer since it is a geometric isomer. Maleic acid is a cis isomer of butenedioic acid. This is due to the fact that two similar atoms in the molecule are on the same side of a double bond.
It is important to note that maleic acid is the cis isomer of butenedioic acid, while fumaric acid is the trans isomer of butenedioic acid .

Note:
Even though, maleic acid and fumaric acid have the same chemical formula they have a difference in their properties due to the difference in their structural formulas. For example, fumaric acid has a high melting point as compared to that of maleic acid.