A rock is 5.0% by mass fayolite(Fe2SiO4), 7.0% by mass forsterite(Mg2SiO4) and the remainder silicon dioxide. What is the mass percent of each element in the rock?
I have the answers but i don't know how to solve the problem.
How would you in steps solve the problem?
I would take a 100g sample which will give you 5.0g of the iron compound, 7.0g of the Mg compound, and 88g SiO2.
5.0g x %Fe in the iron compound = g Fe.
7.0g x %Mg in the Mg compound = g Mg.
%Fe = (gFe/100g)*100
%Mg = )gMg/100g)*100
For Si, compute g Si in the iron cmpd and add to g Si in the Mg cmpd and add to g Si in the SiO2. %Si is done the same way as the others.
I'm sure you get the idea for oxygen.
To solve this problem, you can follow the steps below:
Step 1: Calculate the mass percent of each element.
Given that a rock is 5.0% by mass fayolite, 7.0% by mass forsterite, and the remainder silicon dioxide, we need to find the mass percent of each element (Fe, Si, Mg, and O) in the rock.
Step 2: Convert mass percent to actual mass.
Since the percentages are given by mass, you can assume that the rock has a total mass of 100 grams. Therefore, 5.0 grams of the rock is fayolite, 7.0 grams is forsterite, and the remaining mass is silicon dioxide.
Step 3: Calculate the molar mass of each compound.
Fayolite (Fe2SiO4) consists of two iron (Fe) atoms, one silicon (Si) atom, and four oxygen (O) atoms. Forsterite (Mg2SiO4) consists of two magnesium (Mg) atoms, one silicon (Si) atom, and four oxygen (O) atoms. Silicon dioxide (SiO2) consists of one silicon (Si) atom and two oxygen (O) atoms.
To calculate the molar mass of each compound, you can look up the atomic masses of Fe, Mg, Si, and O from the periodic table, and sum them up according to their chemical formula.
Step 4: Convert grams to moles.
Using the molar masses calculated in step 3, you can convert the masses of fayolite, forsterite, and silicon dioxide to moles by dividing the mass by the molar mass.
Step 5: Calculate the total moles of each element.
Multiply the number of moles obtained from step 4 by the respective stoichiometric ratio of each element in each compound.
For fayolite, you will have a total of 2 moles of Fe, 1 mole of Si, and 4 moles of O.
For forsterite, you will have a total of 2 moles of Mg, 1 mole of Si, and 4 moles of O.
For silicon dioxide, you will have 1 mole of Si and 2 moles of O.
Step 6: Calculate the mass percent for each element.
Using the total moles obtained in step 5, calculate the mass percent of each element by dividing the total moles of the element by the total moles of the rock and multiplying by 100.
For example, the mass percent of Fe can be calculated as (2 moles of Fe / total moles of the rock) * 100.
Following these steps will help you obtain the mass percent of each element in the rock.