How many chlorine atoms would there be in the 145 grams of copper (II) chlorate Cu(ClO3)2? Hint: The molar mass of copper (II) chlorate is 230.45 g/mol.
The Correct Answer and Explanation is:
To find how many chlorine atoms are present in 145 grams of copper (II) chlorate (Cu(ClO₃)₂), we will use the concept of moles, molar mass, and Avogadro’s number.
Step 1: Calculate the number of moles of Cu(ClO₃)₂
The molar mass of copper (II) chlorate is given as 230.45 g/mol. To find the number of moles of Cu(ClO₃)₂ in 145 grams, we divide the mass by the molar mass.Number of moles of Cu(ClO₃)₂=Mass of Cu(ClO₃)₂Molar mass of Cu(ClO₃)₂=145 g230.45 g/mol≈0.629 mol\text{Number of moles of Cu(ClO₃)₂} = \frac{\text{Mass of Cu(ClO₃)₂}}{\text{Molar mass of Cu(ClO₃)₂}} = \frac{145 \, \text{g}}{230.45 \, \text{g/mol}} \approx 0.629 \, \text{mol}Number of moles of Cu(ClO₃)₂=Molar mass of Cu(ClO₃)₂Mass of Cu(ClO₃)₂=230.45g/mol145g≈0.629mol
Step 2: Calculate the number of chlorine atoms
In one formula unit of Cu(ClO₃)₂, there are 2 chlorine (Cl) atoms. Therefore, the total number of chlorine atoms in 0.629 moles of Cu(ClO₃)₂ is:Number of chlorine atoms=Number of moles of Cu(ClO₃)₂×Avogadro’s number×Number of chlorine atoms per formula unit\text{Number of chlorine atoms} = \text{Number of moles of Cu(ClO₃)₂} \times \text{Avogadro’s number} \times \text{Number of chlorine atoms per formula unit}Number of chlorine atoms=Number of moles of Cu(ClO₃)₂×Avogadro’s number×Number of chlorine atoms per formula unitNumber of chlorine atoms=0.629 mol×6.022×1023 atoms/mol×2\text{Number of chlorine atoms} = 0.629 \, \text{mol} \times 6.022 \times 10^{23} \, \text{atoms/mol} \times 2Number of chlorine atoms=0.629mol×6.022×1023atoms/mol×2Number of chlorine atoms≈7.57×1023 atoms\text{Number of chlorine atoms} \approx 7.57 \times 10^{23} \, \text{atoms}Number of chlorine atoms≈7.57×1023atoms
Final Answer:
There are approximately 7.57 × 10²³ chlorine atoms in 145 grams of copper (II) chlorate (Cu(ClO₃)₂).
This approach makes use of moles to convert mass to the number of particles, which is a crucial concept in stoichiometry for understanding how many atoms or molecules are in a given mass of a substance.
