The mass of 6.12 moles of arsenic (As) is calculated to be approximately 459g.
HOW TO CALCULATE MASS:
The mass of a substance can be calculated by multiplying the number of moles of a substance by its molar mass. That is;
Mass of Arsenic = no. of moles of As × molar mass of As.
According to this question, 6.12 moles of arsenic was given and its molar mass is 74.92g/mol.
Mass of As = 6.12 mol × 74.92g/mol
Mass of As = 459g
Therefore, the mass of 6.12 moles of arsenic (As) is calculated to be approximately 459g.
Learn more about mass calculations at: brainly.com/question/8101390
If you mean hydrate as in <em>MgSO4 · 7H2O, </em>then simply find the molar mass of each element you see.
For the example above, that means you would add the molar mass (found on the periodic table) of Mg, then S, then 4(O), 14(H), and 7(O).
The results would be your molar mass for the hydrate.
I hope this is what you meant by your question!
