Question

how many moles of bromine gas are in 37.7 grams?
3.01 × 10³
0.472
0.236
79.9
none of the above

Explanation:

Step1: Recall molar mass of bromine gas

Bromine gas is \(Br_2\). Molar mass of \(Br\) is \(79.9\space g/mol\), so molar mass of \(Br_2\) is \(2\times79.9 = 159.8\space g/mol\).

Step2: Use mole formula

Moles \(n=\frac{mass}{molar\space mass}\). Given mass \(m = 37.7\space g\), molar mass \(M = 159.8\space g/mol\). So \(n=\frac{37.7}{159.8}\).

Step3: Calculate the value

\(\frac{37.7}{159.8}= 0.236\).

Answer:

0.236 (the option with "0.236")