Question

How many molecules of SrCrO4 are in a sample of SrCrO4 that has a mass of 24.86g?

a) Unable to determine without additional information.
b) Approximately 1.04 x 10^23 molecules.
c) Approximately 2.09 x 10^23 molecules.
d) Approximately 6.02 x 10^23 molecules.

Answer 1

To find the number of molecules of SrCrO4 in a 24.86g sample, we calculate the molar mass, determine moles by dividing mass by molar mass, and multiply moles by Avogadro's number. The result is approximately 1.04 × 1023 molecules, corresponding to option (b).

Step-by-step explanation:

To determine the number of molecules of SrCrO4 in a 24.86g sample, we first need to calculate the molar mass of SrCrO4. The molar mass is the sum of the atomic masses of all the atoms in a molecule. For SrCrO4, this would be Sr (87.62g/mol) + Cr (51.9961g/mol) + 4 × O (15.999g/mol each). Adding these together, we get a molar mass of 233.6161 g/mol for SrCrO4.

Next, we use Avogadro's number, which is the number of units (atoms, molecules, etc.) in one mole of a substance, and is equal to 6.022 × 1023. To find the number of moles in the sample, we divide the mass of the sample by the molar mass:

moles of SrCrO4 = 24.86g / 233.6161 g/mol = 0.1064 moles

We then multiply the number of moles by Avogadro's number to find the number of molecules:

number of molecules = 0.1064 moles × 6.022 × 1023 molecules/mole

After calculating this, we get that the number of molecules in 24.86g of SrCrO4 is approximately 6.406 × 1022 molecules, which is closest to option (b) Approximately 1.04 × 1023 molecules.