Answer: The molar mass of KMnO4 is 158.034 g/mol. This means that in 1 mole of KMnO4, there is 1 mole of manganese atoms, which has a molar mass of 54.938 g/mol.
Explanation: To calculate the amount of manganese in a 12.98 g sample of KMnO4, we need to first calculate the number of moles of KMnO4 in the sample:
moles of KMnO4 = mass of sample / molar mass of KMnO4
moles of KMnO4 = 12.98 g / 158.034 g/mol
moles of KMnO4 = 0.082 moles
Since there is 1 mole of manganese in 1 mole of KMnO4, the number of moles of manganese in the sample is also 0.082 moles.
Finally, we can calculate the mass of manganese in the sample:
mass of manganese = moles of manganese x molar mass of manganese
mass of manganese = 0.082 moles x 54.938 g/mol
mass of manganese = 4.50 g
Therefore, there are 4.50 grams of manganese in a 12.98 g sample of KMnO4.