Question

How many NaCl formula units does it contain? Express your answer using two significant figures.

A salt crystal has a mass of 0.16 mg .

Answer 1

Given mass of NaCI 0.16 mg Molar mass of NaCI is 58.4 g/mol Now, calculate the number of moles of NaCI by using following formula: Given mass Molar mass 0.16 mg×1000mg Number of moles in 0.16 mg- 58.4 g/mol 2.74×10-6 mol Formula unit is the smallest possible whole number ratio that a compound contains between its anion and cation. As 1 mole of compound contains 6.023x10 particles or the formula units of NaCl therefore, calculate the number of formula units in 2.74x10- mol of NaCl as shown below: Formula units of NaCL in 0.16 mg = 6.023×1023 × 1mol -1.65 x1018