Comparing fractional abundances for four constraining species with different cosmic-ray ionization rates with a gas density of 10⁷ cm⁻³ for a fast warm-up. CH₃CN with the color key for all four panels (top left), HC₃N (top right), CH₃OCHO (bottom left), and C₂H₅CN gas (bottom right) abundances over time are shown for three cosmic-ray ionization rates (1.3 × 10⁻¹⁷, 1 × 10⁻¹⁶, and 6 × 10⁻¹⁶ s⁻¹). The observed abundances (horizontal lines) for G35.20 A are shown for reference.