Question

a chemist weighed out 1.3 g of calcium. calculate the number of moles of calcium she weighed out. round your answer to 2 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. The molar mass of calcium ($Ca$) is $M = 40.08\ g/mol$.

Step2: Substitute the values into the formula

Given $m = 1.3\ g$ and $M=40.08\ g/mol$, we substitute into $n=\frac{m}{M}$. So $n=\frac{1.3\ g}{40.08\ g/mol}$.

Step3: Calculate the value

$n=\frac{1.3}{40.08}\approx0.0324\ mol$.

Step4: Round to 2 significant digits

Rounding $0.0324$ to 2 significant digits gives $0.032$.

Answer:

$0.032$