Answer:
Hope this helps :)
Step-by-step explanation:
To determine the number of molecules in 765.0 grams of NaCl, we need to first calculate the number of moles of NaCl present in 765.0 grams using its molar mass.
The molar mass of NaCl is 58.44 g/mol (22.99 g/mol for sodium + 35.45 g/mol for chlorine).
Number of moles of NaCl = mass of NaCl / molar mass of NaCl
Number of moles of NaCl = 765.0 g / 58.44 g/mol
Number of moles of NaCl = 13.098 mol
Next, we can use Avogadro's number (6.022 x 10^23) to calculate the number of molecules.
Number of molecules of NaCl = number of moles of NaCl x Avogadro's number
Number of molecules of NaCl = 13.098 mol x 6.022 x 10^23/mol
Number of molecules of NaCl = 7.876 x 10^24 molecules
Therefore, there are approximately 7.876 x 10^24 molecules in 765.0 grams of NaCl.