When a physical change occurs, the arrangement of particles within the substance may change, but the atoms in the molecules remain bonded together.
the 2 next the H indicates that there is two H is one molecule
49.6
0.1 mol / L * 1L/1000mL = 0.0001 mol / mL
using sigs figs
1×10^-4 mol /mL
Answer
× 10²³ molecules are in 41.8 g of sulfuric acid
Explanation
The first step is to convert 41.8 g of sulfuric acid to moles by dividing the mass of sulfuric acid by its molar mass.
Molar mass of sulfuric acid, H₂SO₄ = 98.079 g/mol
Finally, convert the moles of sulfuric acid to molecules using Avogadro's number.
Conversion factor: 1 mole of any substance = 6.022 × 10²³ molecules.
Therefore, 0.426187053 moles of sulfuric acid is equal
Thus, 2.57 × 10²³ molecules are in 41.8 g of sulfuric acid.
To go to mass to number of particles, these are the steps:
Mass divided by molar mass gives moles
moles x avogadros number [will be using 6.02x10^23] gives number of particles.
So:
1.72/128.17 = 0.0134 moles.
0.0134 x 6.02x10^23= 8.07xx10^21 molecules of naphthalene. [rounded to 3 significant figures]