Question

How many atoms are in 9.35g of Calcium?

Answer 1

Answer: there are 1.40 x 10^23 atoms of calcium in a 9.35g sample of this element

Step-by-step explanation:

The question requires us to calculate the amount of atoms in 9.35g of calcium (Ca).

To solve this problem, we can use the Avogadro number: this constant states that there are 6.022 x 10^23 particles (ions, atoms, molecules etc.) in 1 mol of any compound.

First, we need to determine the number of moles of Ca that corresponds to 9.35g of this element.

Knowing that the atomic mass of Ca is 40.078 amu (and its molar mass = 40.078 g/mol), we can calculate the number of moles of Ca using the following equation:

`\begin{gathered} number\text{ of moles = }\frac{mass\text{ \lparen g\rparen}}{molar\text{ mass \lparen g/mol\rparen}} \\ \\ number\text{ of moles \lparen Ca\rparen = }(9.35g)/(40.078g/mol)=0.233mol \end{gathered}`

Therefore, there are 0.233 moles of calcium in 9.35g of this element.

Now that we know the number of moles of Ca, we can apply the Avogadro number to calculate the number of atoms in the given amount of calcium:

1 mol Ca -------------------------- 6.022 * 10^23 atoms Ca

0.233 mol Ca ------------------ x

Solving for x, we'll have:

`x=\frac{(6.022*10^(23)\text{ atoms of Ca\rparen}*(0.233\text{ mol of Ca\rparen}}{(1\text{ mol of Ca\rparen}}=1.40*10^(23)\text{ atoms of Ca}`

Therefore, there are 1.40 x 10^23 atoms of calcium in a 9.35g sample of this element.