Current is defined as the quantity of charge passing a certain point each second given by:

I= Q/t ,where t is time (in seconds) and Q is the charge (in Coulombs).

91.06g of chromium metal (Cr(s)) translates to

n=m/M=91.6g/52.00g/mol= 1.762 mol

Next we must figure out how many electrons are required per reduction reaction.

Cr4+ + 4e- ----> Cr(s), therefore we need 4 electrons per chromium atom to convert it from the oxide to the metal.

#of e- = 4(1.762 mol) = 7.046 mol e-

Lastly we need to convert this number of electrons into a charge (in couloubs).

The charge of one electron is e = 1.6E-19 C, so the total charge is:

Q=(7.046 mol e-)(1.6E-19 C)(6.022E23 e-/mol)= 678900 C

t = (12.4 h)(60min/h)(60s/min)= 44640 s

I= 678900 C/44640 s = 15.2 A

Therefore the current required to produced 91.6 g of chromium metal in 12.4 hours is 15.2 A.

Take Fe(OH)2 as an example where '2' is in subscript. It means that in one formula unit there is one Fe and two hydroxyl (-OH) groups. The two outside the brackets tell us that it apply to not just the oxygen or the hydrogen, but to both of them as a hydroxyl group.

It is an example for a combustion reaction. The matchstick contains sulfur and carbon. Therefore two of the products would be sulfur dioxide and carbon dioxide.

117(g K) * [1.008(g/mol H) / 39.098(g/mol K)] = 3.02 gram hydrogen

When sodium potassium permanganate and hydrogen peroxide interact 30% of oxygen gas is usually produced from the mixture.

Well first things first you have to balance the equation

Fe3O4-->3Fe+2O2

Then because your given mass is in kg you have to convert it to grams

100.0kgx1,000kg/(over)1g=100,000g or 1.0x105

Next because you have mass of Fe3O4 you need to get the molar mass.

(3)55.85gFe+(4)16.00gO=231.55gFe3O4

Now convert grams to moles for your final answer

1.0x105gFe3O4x1mol/(over)231.55g(mm)x3molFe/(over)1mol Fe=1295.6 mol Fe

you can recover 1295.6moles of Fe from Fe3O4

If you follow the rule of Significant Figures, 100.0kg has 4 significant figures (digits) so your answer needs to have 4 digits

1295.6=1296

you can recover 1296 moles of Fe from Fe3O4

Assuming you've asked recently, I can help you. just ask questions and tag it in the chem category and I'll answer them. I'll still be online for a few more hours.- Jen.

Stoichiometry is based on the fact that chemical reactions occur in ratios of moles of all substances. The problem is that there is no device that directly measures moles. We do have a device to measure mass, so molar mass is used in stoichiometric calculations to give results which are measurable.

Step By Step on solving means breaking down a math problem. For example, if you need to find the square root of 12-3, you would need to do the first step and solve 12-3, then go to the next step of what you were asked.

We convert units to moles because in reactions atoms of different elements combine in simple whole-number ratios. The whole numbers are related to the number of atoms, not their weights.

As stated in the category description: "Stoichiometry is a branch of chemistry which deals with the ratios of the reactants and products involved in chemical equations."

Limiting reactants are the reactants that are used up first. And once they are used up, they stop, or limit, the reaction. So the amount of product that can be produced depends on the limiting reactant.

The other reactant, the one in excess, would predict a larger amount of product. But once we produce the amount of product predicted by the limiting reactant. The limiting reactant is used up and the reaction stops.