How many hydrogen atoms are present in 25.3 g of C3H8 (propane)? How many carbon atoms?

27.65×10²³ atoms of H

10.37×10²³ atoms of C

Explanation:

Given data:

Mass of C₃H₈ = 25.3 g

Number of hydrogen atom = ?

Number of carbon atom = ?

Solution:

Number of moles of propane:

Number of moles = mass/molar mass

Number of moles = 25.3 g/ 44.1 g/mol

Number of moles = 0.574 mol

1 mole of propane contain 3 mole of carbon atoms.

0.574 moles of propane contain 0.574  × 3 mol = 1.722 moles of C.

1 mole =  6.022 ×10²³ atoms of C

1.722 mole × 6.022 ×10²³ atoms of C / 1 mol

10.37×10²³ atoms of C

Number of atoms of H:

1 mole of propane contain 8 mole of hydrogen.

0.574 moles of propane contain 0.574  × 8 mol = 4.592 moles of H.

1 mole =  6.022 ×10²³ atoms of H

4.592 mole × 6.022 ×10²³ atoms of H / 1 mol

27.65×10²³ atoms of H

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.