Question

a chemist weighed out 101. g of potassium. calculate the number of moles of potassium she weighed out. be sure your answer has the correct number of significant digits. mol

Explanation:

Step1: Recall the formula for moles

The formula for calculating the number of moles ($n$) is $n=\frac{m}{M}$, where $m$ is the mass and $M$ is the molar mass.

Step2: Determine the molar mass of potassium

The molar mass of potassium ($K$) is $M = 39.10\ \text{g/mol}$.

Step3: Substitute the values into the formula

Given $m = 101\ \text{g}$, then $n=\frac{101\ \text{g}}{39.10\ \text{g/mol}}$.

Step4: Calculate the value

$n=\frac{101}{39.10}\approx 2.58\ \text{mol}$ (rounded to three significant digits as 101 has three significant digits).

Answer:

$2.58$