Question

the image shows polyurethane insulation being sprayed into a wall cavity on a construction site and a lewis structure of a precursor molecule to polyurethane, a diisocyanate, with one of the c=n - c bond angles indicated. polyurethane is one of the most widely used polymer materials in construction engineering, which has a wide variety of uses from foam insulation to structural panels. polyurethanes are made from molecular precursors known as diisocyanates. the lewis structure of a common diisocyanate is shown in the image. based on what you know about vsepr, what would you expect the indicated c - n - c bond angle to be? 90° 109° 120° 180° dont test me yet, i am trying to gain an understanding before attempting to answer this question.

Explanation:

Step1: Identify electron - group geometry

The central N atom in the C - N - C bond has a double - bond to C and single - bonds to other atoms. The nitrogen atom has 3 electron - groups (two single bonds and one double bond). According to VSEPR theory, the electron - group geometry for 3 electron - groups is trigonal planar.

Step2: Determine bond angle

For a trigonal - planar electron - group geometry, the ideal bond angle is 120°.

Answer:

120°