Answer:
7.90×10²¹ formula units
Step-by-step explanation:
From the question given above, the following data were obtained:
Mass of Cu(NO₃)₂ = 2.46 g
Formula units of Cu(NO₃)₂ =?
From Avogadro's hypothesis,
1 mole of Cu(NO₃)₂ = 6.02×10²³ formula units
Next, we shall determine the mass of 1 mole of Cu(NO₃)₂. This can be obtained as follow:
1 mole of Cu(NO₃)₂ = 63.5 + 2[14 + (3×16)]
= 63.5 + 2[14 + 48]
= 63.5 + 2[62]
= 63.5 + 124
= 187.5 g
Thus,
187.5 g of Cu(NO₃)₂ = 6.02×10²³ formula units
Finally, we shall determine the formula units contained in 2.46 g of Cu(NO₃)₂. This can be obtained as follow:
187.5 g of Cu(NO₃)₂ = 6.02×10²³ formula units.
Therefore,
2.46 g of Cu(NO₃)₂ =
(2.46 × 6.02×10²³)/187.5
= 7.90×10²¹ formula units
Thus, 2.46 g of Cu(NO₃)₂ contains 7.90×10²¹ formula units