Question

how many moles of ch4 are in 64.2 g ch4? lets begin by setting up our expression. what should we place in the green box? 64.2 g ch4 a. 16.05 g ch4 b. 1 mole ch4 enter the answer choice letter.

Explanation:

Step1: Determine the molar mass of \(CH_4\)

The molar mass of \(C = 12.01\space g/mol\) and \(H= 1.01\space g/mol\). For \(CH_4\), \(M=(12.01 + 4\times1.01)\space g/mol=16.05\space g/mol\).

Step2: Analyze the unit - conversion factor

We know that \(n=\frac{m}{M}\), where \(n\) is the number of moles, \(m\) is the mass, and \(M\) is the molar mass. To convert grams of \(CH_4\) to moles of \(CH_4\), we use the conversion factor \(\frac{1\space mol\space CH_4}{16.05\space g\space CH_4}\). In the given set - up \(\frac{64.2\space g\space CH_4}{}\times\frac{}{}\), the top part of the second fraction (green box) should be \(1\space mol\space CH_4\) and the bottom part should be \(16.05\space g\space CH_4\)

Answer:

B