How many chloride ions are present in 21.0 grams of CaCl2?
moles chloride ions=molesCaCl2*2
Ag ions=2
To determine the number of chloride ions present in 21.0 grams of CaCl2, we need to use the concept of molar mass and Avogadro's number.
First, we need to find the molar mass of CaCl2. The molar mass is calculated by adding the atomic masses of all the atoms in the compound. The atomic mass of calcium (Ca) is 40.08 g/mol, and the atomic mass of chlorine (Cl) is 35.45 g/mol. Since there are two chlorine atoms in CaCl2, we multiply the atomic mass of chlorine by 2.
Molar mass of CaCl2 = (40.08 g/mol) + 2 × (35.45 g/mol) = 110.98 g/mol
We can now calculate the number of moles of CaCl2 by dividing the given mass (21.0 grams) by the molar mass:
Number of moles = mass / molar mass = 21.0 g / 110.98 g/mol ≈ 0.189 mol
Since there is a 1:2 ratio between CaCl2 and chloride ions (CaCl2 dissociates into one calcium ion and two chloride ions), the number of moles of chloride ions is twice the number of moles of CaCl2.
Number of moles of chloride ions = 2 × 0.189 mol = 0.378 mol
Finally, we can use Avogadro's number to convert the number of moles of chloride ions to the number of chloride ions:
Number of chloride ions = number of moles × Avogadro's number
= 0.378 mol × 6.022 × 10^23 ions/mol
≈ 2.28 × 10^23 chloride ions
Therefore, there are approximately 2.28 × 10^23 chloride ions in 21.0 grams of CaCl2.