In analytical chemistry, hydrated ammonium iron(II) sulfate (commonly known as Mohr's salt) is widely used as a primary standard in redox titrations because of its stability against oxidation in air.
What is the relative formula mass (MrM_rMr) of Mohr's salt, (NH4)2Fe(SO4)2⋅6H2O(\text{NH}_4)_2\text{Fe}(\text{SO}_4)_2 \cdot 6\text{H}_2\text{O}(NH4)2Fe(SO4)2⋅6H2O?
Relative atomic masses (ArA_rAr):
284.0284.0284.0
312.0312.0312.0
378.0378.0378.0
392.0392.0392.0