James needs 4.20 moles of nabr for an experiment. how many grams of nabr must he measure out to have 4.20 moles?

Ans: Mass of NaBr = 432 g

Given:

# moles of NaBr = 4.20 moles

To determine:

The mass corresponding to 4.20 moles of NaBr

Explanation:

The # moles of a given substance is the ratio of its mass to molar mass

moles = mass (g)/molar mass (g.mol-1)(1)

Molar mass of NaBr = 102.89 g/mol

Based on equation(1)

mass = moles * molar mass

        = 4.20 moles * 102.89 g.mol-1 = 432 g

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