Answer:
147 g
Step-by-step explanation:
The number of moles of a substance is the ratio of the mass of the substance and the molar mass of that substance. Mathematically,
mole = mass of substance/molar mass
In this case, Nick needs 3.5 moles of NaF, the molar mass of NaF is calculated as:
23 + 19 = 42 g/mol (Note: Na = 23, F = 19)
Hence,
mass of 3.5 mole NaF = mole x molar mass
= 3.5 x 42 = 147 g.
Hence, Nick would need to measure out 147 g NaF using a suitable weighing balance.