What is the approximate mass of one formula unit of silver nitrate,(AgNO₃)
? \newline [?] x
grams
\newline Enter the coefficient in the green blank and the exponent in the yellow blank. Report your answer to the correct number of significant figures.
The Correct Answer and Explanation is:
The approximate mass of one formula unit of silver nitrate (AgNO₃) is:
2.82 × 10⁻²² grams
Here’s a breakdown of how this value is derived and why it makes sense:
To calculate the mass of a single formula unit of a compound in grams, we begin by finding its molar mass in atomic mass units (amu), then convert that amount to grams using Avogadro’s number. The molar mass of silver nitrate is determined by summing the atomic masses of its constituent atoms:
- Silver (Ag): 107.87 amu
- Nitrogen (N): 14.01 amu
- Oxygen (O): 16.00 amu, and there are three of them
So the total mass of AgNO₃ is:
107.87 + 14.01 + (3 × 16.00) = 107.87 + 14.01 + 48.00 = 169.88 amu
Next, we convert this to grams using the conversion factor:
1 amu = 1.6605 × 10⁻²⁴ grams
Multiplying the molar mass in amu by this conversion factor gives:
169.88 × 1.6605 × 10⁻²⁴ = 2.821 × 10⁻²² grams
Rounded to three significant figures, as justified by the least precise number in the input data, the final answer becomes 2.82 × 10⁻²² grams.
This value represents the mass of a single formula unit, meaning one individual unit of AgNO₃ as it exists in a crystal lattice or dissolved in solution. Since the formula unit reflects the smallest whole-number ratio of ions in the compound, this calculation ties together molar mass concepts, unit analysis, and significant figures.
So, enter:
- Coefficient (green box): 2.82
- Exponent (yellow box): –22
