Determine the number of particles in this sample. Identify the unit as a formula unit or a molecule. 58 g of chromium (III) sulfate.
To determine the number of particles in a sample, you need to use the concept of moles and Avogadro's number.
First, you need to calculate the number of moles of chromium (III) sulfate in the sample. To do this, you need to use the formula mass of chromium (III) sulfate, which is the sum of the atomic masses of all the elements in the compound.
The molar mass of chromium (III) sulfate (Cr2(SO4)3) can be calculated as follows:
- Chromium (Cr) has an atomic mass of 52 g/mol.
- Sulfur (S) has an atomic mass of 32 g/mol.
- Oxygen (O) has an atomic mass of 16 g/mol.
Therefore, the molar mass of Cr2(SO4)3 is:
(2 * 52 g/mol) + (3 * (32 g/mol + 4 * 16 g/mol)) = 392 g/mol.
Next, you can calculate the number of moles using the formula:
moles = mass / molar mass.
For the given sample of 58 g of chromium (III) sulfate:
moles = 58 g / 392 g/mol = 0.147 moles.
Now, to determine the number of particles (atoms, ions, or molecules) in the sample, you need to multiply the number of moles by Avogadro's number. Avogadro's number is defined as 6.022 * 10^23 particles/mol.
Number of particles = moles * Avogadro's number
= 0.147 mol * 6.022 * 10^23 particles/mol.
The unit for chromium (III) sulfate is based on its chemical formula, which is Cr2(SO4)3. So, in this case, the unit is a formula unit.
Therefore, the number of particles in 58 g of chromium (III) sulfate is approximately:
0.147 mol * 6.022 * 10^23 particles/mol ≈ 8.857 * 10^22 particles.