3.) 2.46 grams of Cu(NO3)2 would contain how many formula units?

7.90×10²¹ formula units

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