  $Context.$ On October 31, 2009, the Photodetector Array Camera and
Spectrometer (PACS) on board the Herschel Space Observatory observed
far-infrared spectra of Jupiter between 50 and 220$\,\mu$m as part of the
program "Water and Related Chemistry in the Solar System". $Aims.$ We
investigate the disk-averaged chemical composition of Jupiter's atmosphere as a
function of height using these observations. $Methods.$ We used the Planetary
Spectrum Generator (PSG) and the least-squares fitting technique to infer the
abundances of trace constituents. $Results.$ The PACS data include numerous
spectral lines attributable to ammonia (NH$_3$), methane (CH$_4$), phosphine
(PH$_3$), water (H$_2$O), and deuterated hydrogen (HD) in the Jovian
atmosphere. We infer an ammonia abundance profile that decreases from a mole
fraction of $(1.7\pm 0.8)\times 10^{-4}$ at $p\sim 900\,$mbar to $(1.7\pm
0.9)\times 10^{-8}$ at $p\sim 275\,$mbar, following a fractional scale height
of about 0.114. For phosphine, we find a mole fraction of $(7.2\pm 1.2)\times
10^{-7}$ at pressures higher than $(550\pm 100)\,$mbar and a decrease of its
abundance at lower pressures following a fractional scale height of $(0.09\pm
0.02)$. Our analysis delivers a methane mole fraction of $(1.49\pm 0.09)\times
10^{-3}$. Analyzing the HD $R(0)$ line at $112.1\,\mu$m yields a new
measurement of Jupiter's D/H ratio, $\text{D/H}=(1.5\pm 0.6)\times 10^{-5}$.
Finally, the PACS data allow us to put the most stringent $3\sigma$ upper
limits yet on the mole fractions of hydrogen halides in the Jovian troposphere.
These new upper limits are $<1.1\times 10^{-11}$ for hydrogen fluoride (HF),
$<6.0\times 10^{-11}$ for hydrogen chloride (HCl), $<2.3\times 10^{-10}$ for
hydrogen bromide (HBr) and $<1.2\times 10^{-9}$ for hydrogen iodide (HI) and
support the proposed condensation of hydrogen halides into ammonium halide
salts in the Jovian troposphere.
