SECTION ONE: Mass, Moles and Avogadro's Number Question One (Knowledge/4) How many molecules of sodium chloride are in a $10 \mathrm{~g}$ sample?

Step 1 ：Find the molar mass of sodium chloride (NaCl): Molar mass of Na = 22.99 g/mol, Molar mass of Cl = 35.45 g/mol, Molar mass of NaCl = 58.44 g/mol

Step 2 ：Calculate the number of moles of NaCl in the 10g sample: moles = \(\frac{mass}{molar~mass}\) = \(\frac{10}{58.44}\) = 0.1711 moles

Step 3 ：Use Avogadro's number to find the number of molecules: molecules = moles * Avogadro's number = 0.1711 * 6.022 x 10^23 = 1.03 x 10^23

Step 4 ：\(\boxed{1.03 \times 10^{23}}\) molecules of sodium chloride in a 10g sample