Question

The number of grams of P in 1 mol weight of H3PO4?

I know the answer is 30.97 but the way the teachers wants it solved is with avogadro's number, and Im not sure how to do it that way.

Answer 1

Answer 2

Avogadro's number is used to convert the number of moles to the number of molecules or atoms in a substance, or vice versa. It is defined as the number of atoms in 12 grams of carbon-12, which is approximately 6.022 x 10^23.

To solve the problem using Avogadro's number, you can follow these steps:

1. Write the chemical formula for H3PO4.

2. Calculate the molar mass of H3PO4 by adding the atomic masses of each element:

• Atomic mass of H = 1.008 g/mol

• Atomic mass of P = 30.974 g/mol

• Atomic mass of O = 15.999 g/mol (there are 4 O atoms in H3PO4) Molar mass of H3PO4 = (3 x 1.008) + 30.974 + (4 x 15.999) = 98.0 g/mol

3. Use Avogadro's number to find the number of molecules in 1 mol of H3PO4:

• 1 mol of H3PO4 contains 6.022 x 10^23 molecules

4. Calculate the mass of P in 1 mol of H3PO4 by multiplying the number of P atoms by the atomic mass of P:

• There is 1 P atom in H3PO4, so the mass of P in 1 mol of H3PO4 is 30.974 g/mol.

5. Therefore, the number of grams of P in 1 mol of H3PO4 is 30.974 g/mol.

So, the answer is 30.974 g/mol, which is approximately equal to 30.97 g/mol (when rounded to two decimal places).