How many potassium ions are present in 91.1g of potassium nitrate?
To determine the number of potassium ions present in a sample of potassium nitrate, you need to use the molar mass and Avogadro's number.
1. Calculate the molar mass of potassium nitrate (KNO3).
- The molar mass of potassium (K) is 39.10 g/mol.
- The molar mass of nitrogen (N) is 14.01 g/mol.
- The molar mass of oxygen (O) is 16.00 g/mol.
Hence, the molar mass of KNO3 is calculated as follows:
Molar mass of KNO3 = (1 x Molar mass of K) + (1 x Molar mass of N) + (3 x Molar mass of O)
Molar mass of KNO3 = (1 x 39.10 g/mol) + (1 x 14.01 g/mol) + (3 x 16.00 g/mol)
2. Calculate the number of moles of KNO3.
To find the number of moles, divide the mass of the sample (91.1 g) by the molar mass of KNO3 calculated in step 1. Assume that the complete sample consists of potassium nitrate.
Number of moles of KNO3 = Mass / Molar mass
Number of moles of KNO3 = 91.1 g / Molar mass of KNO3
3. Use Avogadro's number to convert moles to the number of potassium ions.
Avogadro's number is 6.022 x 10^23 particles per mole. Since there is one potassium (K) ion per potassium nitrate molecule, the number of potassium ions will equal the number of moles of KNO3 multiplied by Avogadro's number.
Number of potassium ions = Number of moles of KNO3 x Avogadro's number
Now, plug in the values, calculate, and round off the answer to the appropriate number of significant figures.