The formula for cobalt(II) nitrate is Co(NO3)2

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Co(NO3)2
The formula for cobalt(II) nitrate is Co(NO3)2.

a. How many grams of cobalt(II) nitrate are present in formula 9.60 x 10^21 units of this compound?____grams

b.How many formula units of cobalt(II) nitrate are present in 2.41 grams of this compound?

________formula units

The Correct Answer and Explanation is :

To answer these questions, we need to follow the steps involved in converting between moles, grams, and formula units. We will use the molar mass and Avogadro’s number to help us with these conversions.

Given Information:

  • The formula for cobalt(II) nitrate is Co(NO₃)₂.
  • The molar mass of Co(NO₃)₂ is calculated from the atomic masses of cobalt (Co), nitrogen (N), and oxygen (O):
  • Co: 58.93 g/mol
  • N: 14.01 g/mol
  • O: 16.00 g/mol

Thus, the molar mass of Co(NO₃)₂ is:
[ 58.93 \, \text{g/mol} + 2 \times (14.01 \, \text{g/mol} + 3 \times 16.00 \, \text{g/mol}) ]
[ = 58.93 + 2 \times (14.01 + 48.00) ]
[ = 58.93 + 2 \times 62.01 ]
[ = 58.93 + 124.02 = 182.95 \, \text{g/mol} ]

Part (a) – How many grams of cobalt(II) nitrate are present in 9.60 × 10²¹ formula units of Co(NO₃)₂?

We can use the following steps:

  1. Calculate moles of Co(NO₃)₂:
  • Use Avogadro’s number (6.022 × 10²³ formula units per mole) to convert the formula units to moles:
    [
    \text{Moles of Co(NO₃)₂} = \frac{9.60 \times 10^{21}}{6.022 \times 10^{23}} = 1.59 \times 10^{-2} \, \text{mol}
    ]
  1. Convert moles to grams:
  • Multiply the moles by the molar mass of Co(NO₃)₂:
    [
    \text{Mass in grams} = 1.59 \times 10^{-2} \, \text{mol} \times 182.95 \, \text{g/mol} = 2.91 \, \text{grams}
    ]

So, the mass of 9.60 × 10²¹ formula units of cobalt(II) nitrate is 2.91 grams.

Part (b) – How many formula units of cobalt(II) nitrate are present in 2.41 grams of Co(NO₃)₂?

We can use the following steps:

  1. Calculate moles of Co(NO₃)₂:
  • Use the molar mass to convert grams to moles:
    [
    \text{Moles of Co(NO₃)₂} = \frac{2.41 \, \text{grams}}{182.95 \, \text{g/mol}} = 1.32 \times 10^{-2} \, \text{mol}
    ]
  1. Convert moles to formula units:
  • Multiply the moles by Avogadro’s number to find the number of formula units:
    [
    \text{Formula units} = 1.32 \times 10^{-2} \, \text{mol} \times 6.022 \times 10^{23} \, \text{formula units/mol} = 7.96 \times 10^{21} \, \text{formula units}
    ]

So, the number of formula units in 2.41 grams of cobalt(II) nitrate is 7.96 × 10²¹ formula units.

Summary:

  • (a) 9.60 × 10²¹ formula units of Co(NO₃)₂ correspond to 2.91 grams of the compound.
  • (b) 2.41 grams of Co(NO₃)₂ correspond to 7.96 × 10²¹ formula units.

Let me generate the image explaining the process visually for you.

Here is an educational diagram showing the conversion between formula units, moles, and grams for cobalt(II) nitrate. It demonstrates how to use Avogadro’s number and the molar mass to perform the conversions.

Let me know if you need any further explanations or adjustments!

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