The weight of one mole of antimatter can be calculated using the concept of molar mass. Molar mass is the mass of one mole of a substance and is expressed in grams per mole (g/mol). The molar mass of a substance is equal to its atomic or molecular weight.
Antimatter consists of antiparticles, which are counterparts of normal matter particles but with opposite charge. For example, the antiparticle of an electron is called a positron, and the antiparticle of a proton is called an antiproton.
The molar mass of antimatter can be calculated by summing the masses of its constituent antiparticles. The masses of antiparticles are the same as their corresponding matter particles, but their charges are opposite.
For example, the molar mass of antimatter composed of one mole of antiprotons (mass of a proton = 1.0073 atomic mass units or amu) and one mole of positrons (mass of an electron = 0.00054858 amu) would be:
Molar mass of antimatter = (1 mole of antiprotons * mass of a proton) + (1 mole of positrons * mass of an electron)
= (1 mole * 1.0073 amu) + (1 mole * 0.00054858 amu)
= 1.0073 amu + 0.00054858 amu
= 1.00784858 amu
Please note that the actual molar mass of specific antimatter compositions may vary depending on the specific antiparticles involved. The example above serves to illustrate the calculation method based on the masses of antiparticles.