Question

James needs 4.20 moles of NaBr for an experiment. How many grams of NaBr must he measure out to have 4.20 moles? A. 24.5 B. 103 C. 183 D. 432

Answer 1

(a) is the correct answer

Answer 2

Answer: 432 grams of NaBr must he measure out to have 4.20 moles.

Solution:

Moles of NaBr required for the experiment = 4.20 moles

Mass required for 4.20 moles of NaBr = $x$ grams

Molecular weight of NaBr = 102.8 g/mol

Number of moles of NaBr = $\frac{\text{Mass of the NaBr}}{\text{Molecular mass of NaBr}}=$

$4.20=\frac{x g}{102.8 g/mol}$

$x=4.20mol\times 102.8 g/mol=431.76 g\approx432 grams$

432 grams of NaBr must he measure out to have 4.20 moles.