Question

A 0.244 g sample of calcium carbonate, CaCO₃, was recovered from a sample of hard water. How many formula units of CaCO₃ were in the sample?

A) Calculate the formula units
B) Measure the calcium content
C) Analyze the water sample
D) None of the above

Answer 1

To find the number of formula units of CaCO3 in a 0.244 g sample, first calculate the moles by dividing the mass by the molar mass, then multiply the result by Avogadro's number, yielding approximately 1.47 × 1021 formula units.

Step-by-step explanation:

The question is asking for the number of formula units in a given amount of calcium carbonate (CaCO3). To calculate this, we use Avogadro's number which is 6.022 × 1023 formula units per mole.

1. First, we calculate the number of moles of CaCO3 using the mass of the sample (0.244 g) and the molar mass of CaCO3 (100.0869 g/mol).
2. Next, we multiply the number of moles by Avogadro's number to get the total number of formula units.

Number of moles = Mass / Molar mass = 0.244 g / 100.0869 g/mol = 0.00244 moles of CaCO3

Formula units = Number of moles × Avogadro's number = 0.00244 moles × 6.022 × 1023 units/mole = 1.47 × 1021 formula units of CaCO3