To calculate the vibrational frequency and corresponding infrared spectrum of ammonia NH3 at room temperature, we need to consider its molecular structure and the types of vibrations it can undergo. Ammonia has a trigonal pyramidal structure with nitrogen at the apex and three hydrogen atoms at the base. It has a total of 3N-6 where N is the number of atoms vibrational modes for a non-linear molecule, which equals 3 4 -6 = 6 vibrational modes.These 6 vibrational modes can be classified into two types: stretching and bending. There are three N-H stretching modes symmetric, asymmetric, and doubly degenerate and three N-H bending modes symmetric, asymmetric, and doubly degenerate .The vibrational frequencies of these modes can be experimentally determined or theoretically calculated using force constants and reduced masses. The experimental values for the vibrational frequencies of ammonia are:1. Symmetric N-H stretching 1 : ~3336 cm2. Asymmetric N-H stretching 3 : ~3360 cm3. Doubly degenerate N-H stretching 2 : ~1625 cm4. Symmetric N-H bending 4 : ~1095 cm5. Asymmetric N-H bending 6 : ~1095 cm6. Doubly degenerate N-H bending 5 : ~1625 cmThe corresponding infrared spectrum of ammonia at room temperature will show absorption bands at these vibrational frequencies. However, not all vibrational modes are IR-active. To be IR-active, a vibrational mode must result in a change in the molecule's dipole moment. In the case of ammonia, the symmetric stretching 1 and doubly degenerate bending 5 modes are IR-active, while the others are not.Therefore, the infrared spectrum of ammonia at room temperature will show two main absorption bands at ~3336 cm symmetric N-H stretching and ~1625 cm doubly degenerate N-H bending .