Question

What is the formula mass for potassium nitrate? Hint: Atomic mass Potassium (K) - 39.10 amu; Atomic mass Oxyden (O) - 16 amu; Atomic Mass Nitrogen (N) - 14.01 amu. The formula for Nitrate ion - NO3-

a. 92.99 amu
b. 117.11 amu
c. 85.11 amu
d. 101.10 amu
e. none of the above

Answer 1

The formula mass for potassium nitrate KNO3 is the sum of the atomic masses of its constituent atoms which gives a total of
`101.10 amu`.

Step-by-step explanation:

The formula mass for potassium nitrate is calculated by summing the atomic masses of all the atoms present in the formula KNO3. The atomic mass of Potassium (K) is
`39.10 amu`, Nitrogen (N) is
`14.01 amu`, and each Oxygen (O) is
`16 amu`. Potassium nitrate contains one potassium atom, one nitrogen atom and three oxygen atoms.

The calculation is as follows:

• • 
    `K: 1 x 39.10 = 39.10 amu`
  • 
    `N: 1 x 14.01 = 14.01 amu`
  • 
    `O: 3 x 16 = 48.00 amu`

Adding these together gives a total formula mass of:

`39.10 amu (K) + 14.01 amu (N) + 48.00 amu (O) = 101.10 amu`

Therefore the correct answer is
`101.10 amu`.