How many grams in 4.00 moles of Fe2O3?
Answer
4 Moles
Mass = 159.7 grams
4 X 159.7/1 = 6.388 or 6.39 grams.
How do you get 6.39X102grams?
Fe is +2 and O is –2. you have 2-Fe and 3-O why would this not be 6.39X10-2 grams
To calculate the number of grams in 4.00 moles of Fe2O3, you need to use the molar mass of Fe2O3.
Fe2O3 consists of two iron (Fe) atoms and three oxygen (O) atoms. The molar mass of Fe2O3 can be determined by adding up the atomic masses of the individual elements. The atomic mass of Fe is approximately 55.845 grams and the atomic mass of O is approximately 16.00 grams.
To calculate the molar mass of Fe2O3, you multiply the atomic masses of Fe and O by their respective subscripts and add them together:
(2 x atomic mass of Fe) + (3 x atomic mass of O) = (2 x 55.845 g/mol) + (3 x 16.00 g/mol) = 111.69 g/mol + 48.00 g/mol = 159.69 g/mol
Therefore, the molar mass of Fe2O3 is approximately 159.69 grams per mole.
To find the number of grams in 4.00 moles of Fe2O3, you can use the formula:
number of grams = number of moles x molar mass
Plugging in the values:
number of grams = 4.00 moles x 159.69 grams/mole = 638 grams
So, 4.00 moles of Fe2O3 is equal to 638 grams.
Regarding your second question, 6.39 x 10^2 grams is another way of expressing the value 6.39 x 100 grams. It is in scientific notation, where the exponent "2" denotes the number of places the decimal point should be shifted to the right. Therefore, 6.39 x 10^2 grams is equivalent to 639 grams, not 6.39 x 10^-2 grams.
The reason why the value is not 6.39 x 10^-2 grams is because, in the compound Fe2O3, the oxidation state of Fe is +3, not +2 as you mentioned. In Fe2O3, each Fe atom is bonded to three oxygen atoms, and oxygen has an oxidation state of -2. Therefore, the overall charge of the compound must be neutral, which means that the sum of the oxidation states must equal zero.
To find the oxidation state of Fe in Fe2O3, you can set up the following equation:
(2 x oxidation state of Fe) + (3 x oxidation state of O) = 0
Solving for the oxidation state of Fe gives:
2(oxidation state of Fe) + 3(-2) = 0
2(oxidation state of Fe) = 6
oxidation state of Fe = 3
Therefore, Fe in Fe2O3 has an oxidation state of +3, and not +2.