In order to do that we will use the molar mass of H3PO4, which is 98 g/mol, that means that for each mol of H3PO4, we will have 98 grams of it, but what about 4.5 moles:
1 mol = 98 g
4.5 moles = x grams
x = 441 grams of H3PO4
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