Question

a student sets up the following equation to solve a problem in solution stoichiometry. (the ? stands for a number the student is going to calculate.) enter the units of the students answer. $\frac{(0.10 l)(\frac{1 ml}{10^{-3} l})(2.00 \frac{g}{ml})}{(121.28 \frac{g}{mol})}=?square$

Explanation:

Step1: Analyze unit - conversion of volume

The first two factors convert the volume from liters (L) to milliliters (mL). The factor $\frac{1\ mL}{10^{-3}\ L}$ is used for volume - unit conversion. The unit of volume after this step is mL.
$(0.10\ L)\times\frac{1\ mL}{10^{-3}\ L}$

Step2: Multiply by mass - per - volume factor

The next factor $\frac{2.00\ g}{mL}$ is a mass - per - volume factor. When we multiply the volume (in mL) by this factor, the mL units cancel out and we get the mass in grams.
$(0.10\ L)\times\frac{1\ mL}{10^{-3}\ L}\times\frac{2.00\ g}{mL}$

Step3: Divide by molar - mass factor

The last factor $\frac{1}{ \frac{121.28\ g}{mol}}$ is the reciprocal of the molar - mass. When we divide the mass (in g) by the molar - mass (g/mol), the gram (g) units cancel out and we are left with moles (mol).
$\frac{(0.10\ L)\times\frac{1\ mL}{10^{-3}\ L}\times\frac{2.00\ g}{mL}}{\frac{121.28\ g}{mol}}$

Answer:

mol