We develop an existing 1-D photochemistry model to include a comprehensive description of organic chemistry on Mars that includes the oxidation products of methane (CH$_4$) and ethane (C$_2$H$_6$), a longer-chain hydrocarbon that can be used to differentiate between abiotic and biotic surface releases of CH$_4$. We find that CH$_4$ is most volatile between 20–50 km during Mars’ northern summer, where the local atmospheric CH$_4$ lifetime lowers to 25–60 years. We study atmospheric formaldehyde (HCHO) and formic acid (HCOOH), as the two common oxidation products of CH$_4$ and C$_2$H$_6$, and acetaldehyde (CH$_3$CHO) and acetic acid (CH$_3$COOH) as unique products of C$_2$H$_6$. We focus our analysis of these gases at Mars’ aphelion and perihelion at latitudes between -30$^{\circ}$ and 30$^{\circ}$, altitudes from the surface to 70 km, and from a homogeonous initial condition of 50 pptv of CH$_4$ and C$_2$H$_6$. From this initial condition, CH$_4$ produces HCHO in a latitude-independent layered structure centred at 20–30 km at aphelion with column-averaged mixing ratios of 10$^{-4}$ pptv, and oxidation of C$_2$H$_6$ produces HCHO at 10$^{-2}$ pptv. Formic acid has an atmospheric lifetime spanning 1–10 sols below 10 km that shows little temporal or zonal variability, and is produced in comparable abundances (10$^{-5}$ pptv) by the oxidation of C$_2$H$_6$ and CH$_4$. We also find that oxidation of 50 pptv of C$_2$H$_6$ results in 10$^{-3}$ pptv of CH$_3$CHO and 10$^{-4}$ pptv of CH$_3$COOH. Subsequent UV photolysis of this CH$_3$CHO results in 10$^{-4}$ pptv of atmospheric CH$_4$, potentially representing a new atmospheric source of Martian CH$_4$.