Question

a chemist weighed out 5.9 g of tin. calculate the number of moles of tin she weighed out. be sure your answer has the correct number of significant digits.

Explanation:

Step1: Recall molar - mass formula

The formula to calculate the number of moles $n$ is $n=\frac{m}{M}$, where $m$ is the mass and $M$ is the molar mass. The molar mass of tin (Sn) is $M = 118.71\ g/mol$.

Step2: Substitute values

We are given $m = 5.9\ g$ and $M=118.71\ g/mol$. Substitute these values into the formula: $n=\frac{5.9\ g}{118.71\ g/mol}$.

Step3: Calculate the number of moles

$n=\frac{5.9}{118.71}\ mol\approx0.0497\ mol$. Rounding to two significant digits (since 5.9 has two significant digits), $n = 0.050\ mol$.

Answer:

$0.050$ mol