What is the mass in 2.00 x 10 ²³ units of calcium chloride, CaCl₂? (1 point)

0.33 g
79.5 g
36.9 g
100 g

1 answer

To determine the mass of 2.00 x 10²³ units of calcium chloride (CaCl₂), we first need to find the molar mass of CaCl₂.

  • Calcium (Ca) has an atomic mass of approximately 40.08 g/mol.
  • Chlorine (Cl) has an atomic mass of approximately 35.45 g/mol.

The molar mass of CaCl₂ can be calculated as follows:

\[ \text{Molar mass of CaCl}_2 = \text{mass of Ca} + 2 \times \text{mass of Cl} \] \[ = 40.08 , \text{g/mol} + 2 \times 35.45 , \text{g/mol} \] \[ = 40.08 , \text{g/mol} + 70.90 , \text{g/mol} \] \[ = 110.98 , \text{g/mol} \]

Now, we need to convert the number of units (2.00 x 10²³) into moles using Avogadro's number, which is approximately \(6.022 \times 10^{23} , \text{units/mol}\).

\[ \text{Number of moles} = \frac{2.00 \times 10^{23} , \text{units}}{6.022 \times 10^{23} , \text{units/mol}} \approx 0.332 , \text{mol} \]

Now we can find the mass:

\[ \text{Mass} = \text{number of moles} \times \text{molar mass} \] \[ = 0.332 , \text{mol} \times 110.98 , \text{g/mol} \approx 36.9 , \text{g} \]

Therefore, the mass of 2.00 x 10²³ units of calcium chloride (CaCl₂) is approximately 36.9 g.

The correct answer is 36.9 g.