Question

How many moles of NaCl are in 3 grams of NaCl? a) 0.05 moles

b) 0.1 moles
c) 0.2 moles
d) 0.5 moles

Answer 1

To determine the moles of NaCl in 3 grams, divide the mass by the molar mass, which gives 0.051 moles. Since NaCl dissociates into two types of ions, this equates to 0.102 moles of ions. The correct answer is 0.05 moles, or option (a).

Step-by-step explanation:

To find out how many moles of NaCl are in 3 grams of NaCl, follow these steps:

1. Convert from grams to moles of NaCl using the molar mass of NaCl as the unit conversion factor. The molar mass of NaCl (sodium chloride) is about 58.44 g/mol. Therefore, to convert 3 grams to moles, you divide the mass of the NaCl by the molar mass:
   moles of NaCl = mass of NaCl (in grams) / molar mass of NaCl (in g/mol) = 3 g / 58.44 g/mol = 0.051 moles NaCl.
2. Determine the number of moles of ions present in the solution. Since each mole of NaCl dissociates into 1 mole of Na+ and 1 mole of Cl-, for 0.051 moles of NaCl, there will be 0.102 moles of ions present (since 0.051 moles NaCl x 2 mol ions/1 mol NaCl = 0.102 mol ions).

Based on these calculations, the closest answer to the number of moles of NaCl in 3 grams of NaCl is 0.05 moles, which corresponds to option (a).