Question

55.7 grams of calcium (ca) = ______ moles of calcium
calcium 20
ca
40.078
1.39 moles of calcium
0.720 moles of calcium
1.25 moles of calcium
1.00 moles of calcium

Explanation:

Step1: Recall mole - 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.

Step2: Identify given values

Given $m = 55.7$ g (mass of calcium) and from the periodic - table, $M=40.078$ g/mol (molar mass of calcium).

Step3: Calculate the number of moles

$n=\frac{55.7}{40.078}\approx1.39$ mol.

Answer:

1.39 moles of Calcium