Number of moles is found by formula n=mass/molar mass, or m/M. the molar mass is found by adding together the atomic masses of Na and Cl (22.99 + 35.45) to give 58.44 g/mol. Since the mass of NaCl is 75.0g, we find the number of moles as follows: n = 75.0 / 58.44 = 1.28 mol
To find the number of moles of any compound you should divide the mass over the molar mass of that compound
<span>so for your question, </span>
<span>number of moles = mass/ molar mass </span> <span>= 75.0 g / 58.443 g/mol </span> <span>= 1.2833 </span> <span>= 1.28 and note that the answer is rounded to 3 significant figures</span>
