Calculate moles from provided weight

4. Moles and Molarity 4.1) Moles 4.1.1) Moles - General

4.1.1.1) Moles - General Normal 1


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A compounder weighed 44.7615 mg of NaBr . If the molecular weight of NaBr is 102.9 g/mol, then determine the number of milimoles present there.


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lb equals 0.435 mmol kg

    The molecular weight of NaBr is 102.9 g/mol, which means `(102.9 \quad g)/(1 \quad mol)`. Again, 44.7615 mg equals `44.7615/1000=0.0447615` g of NaBr . Therefore, using equation method we can write:
    `(102.9 \quad g)/(1 \quad mol)=(0.0447615 \quad g)/x therefore x = 0.000435` mol.
    Multiplying this number with 1000 will give us milimoles;
    `therefore 0.000435 × 1000 = 0.435` mmol. Ans.

    Using shortcut: simply divide the miligram weight (`44.7615 \quad mg`) with molecular weight (`102.9\quad g/(mol)`). This will give us:
    `(44.7615 \quad mg)/(102.9 \quad g/(mol))=0.435 \quad mmol` Ans.


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