Question

question 14 if a box of cacl₂ has a mass of 2.56 g. blank 1 moles are in the box. blank 2x10^blank 3 atoms are in the box. blank 1 add your answer blank 2 add your answer blank 3 add your answer

Explanation:

Step1: Calculate molar mass of CaCl₂

The molar mass of Ca ($M_{Ca}=40.08\ g/mol$) and Cl ($M_{Cl} = 35.45\ g/mol$). For CaCl₂, $M = 40.08+2\times35.45=40.08 + 70.9=110.98\ g/mol$.

Step2: Calculate moles of CaCl₂

Use the formula $n=\frac{m}{M}$, where $m = 2.56\ g$ and $M = 110.98\ g/mol$. So $n=\frac{2.56}{110.98}\approx0.0231\ mol$. This is the answer for Blank 1.

Step3: Calculate number of formula - units of CaCl₂

Use Avogadro's number $N_A=6.022\times 10^{23}\ mol^{-1}$. The number of formula - units of CaCl₂, $N=n\times N_A=0.0231\times6.022\times 10^{23}=1.3911\times10^{22}$ formula - units. Since each formula - unit of CaCl₂ contains 3 atoms (1 Ca and 2 Cl), the number of atoms $N_{atoms}=3\times N = 3\times1.3911\times 10^{22}=4.1733\times10^{22}$ atoms. We can write it as $4.17\times 10^{22}$ atoms. So Blank 2 = 4.17 and Blank 3 = 22.

Answer:

Blank 1: 0.0231
Blank 2: 4.17
Blank 3: 22