Question

Please answer all!

1. What is the empirical formula of C8H6O3?

2. What is the mass of 0.0400 moles of potassium carbonate?

3. What is the mass of 0.0500 moles of aluminum sulfate?

4. A sample of calcium that contains twice Avogadro’s number of atoms has a mass of ___?

Answer 1

Solution :

1.  The empirical formula of a chemical compound is the simplest positive integer ratio of atoms present in a compound.

So, empirical formula of the compound is : C₈H₆O₃ (same as given)

2. Molar mass of Potassium carbonate(K₂CO₃) = 138.2 g/mol

We can also say that, mass of 1 mole of Potassium carbonate = 138.2 g

So, mass of 0.0400 mole of Potassium carbonate = 138.2 0.0400 = 5.528 g

Therefore, the mass of 0.0400 moles of potassium carbonate = 5.528 g

3. Molar mass of Aluminum sulfate(Al₂(SO₄)₃) = 342.15 g/mol

We can also say that, mass of 1 mole Aluminum sulfate = 342.15 g

So, mass of 0.0500 mole aluminum sulfate = 342.15 0.0500 = 17.1075 g

Therefore, the mass of 0.0500 moles of aluminum sulfate = 17.1075 g

4. 1 mole of calcium contains = 6.022 10²³ atoms = Avogadro's number of atoms.

Twice Avogadro's number af atoms = 2 moles of calcium

Molar mass of Calcium = 40.078 g/mol

So, mass of 2 moles of Calcium = 80.156 g.

Therefore, a sample of calcium that contains twice Avogadro’s number of atoms has a mass of = 80.156 g