Sapling week 7/8 #18

[Uyenvy Nguyen 1D]

I put 4Fe(s)+3O2(g)+6H2O(l)↽−−⇀2Fe2O3(s)∙6H2O(s) for the question below, and I also tried it without the phases, but it still says it's incorrect. How would I balance this?:

One of the most recognizable corrosion reactions is the rusting of iron. Rust is caused by iron reacting with oxygen gas in the presence of water to create an oxide layer.

Iron can form several different oxides, each having its own unique color. Red rust is caused by the formation of iron(III) oxide trihydrate.

Fe2O3∙3H2O

Write the balanced reaction for the formation of Fe2O3∙3H2O(s) . Phases are optional.

[Uyenvy Nguyen 1D]

oops ignore the image being attached 3 times

[vanessanguyen3I]

I am struggling with the same issue!! and everything seems balanced

[cadytran1K]

Everything is right except for the 6H2O in product. It should be 3H2O

[chinmayeec 2H]

Fe2O3*3H2O is a compound itself and you don't multiply the coefficient (2) into the chemical formula. So the product would be 2Fe2O3*3H2O

Hope that helps!

[Uyenvy Nguyen 1D]

Thank you !!!

[Jaclyn Schwartz 1I]

Thank you this helps alot! I have been stumped

[Aliya Roserie 3I]

Thank you!

[Aliya Roserie 3I]

I agree, super helpful

[Simrah_Ahmed1J]

Basically for this equation, since Fe2O3∙3H2O is one compound, any coefficient you put in front of Fe2O3 also applies to 3H2O, you don't need any other notation or parenthesis or anything, just #Fe2O3∙3H2O (# being the coefficient).

[Jeremy Wei 2C]

Thanks! It was really helpful!

[505706331]

how do you know that you have to separate the fe and o as o2?

[Alyssa Cua 2J]

Basically for this equation, since Fe2O3∙3H2O is one compound, any coefficient you put in front of Fe2O3 also applies to 3H2O, you don't need any other notation or parenthesis or anything, just #Fe2O3∙3H2O (# being the coefficient).

Thanks so much for explaining! I was stuck on this one.

[sophiavmr]

What does the black dot mean?

[Genelle Marcelino-Searles 2G]

Since the 3H2O has that dot, it means it is one compound with the Fe2O3, so you don't need to multiply the 3 in the H2O. If you just put it in front of the Fe2O3, it is multiplied into the 3H2O since it's one compound.

[Ally Mosher]

What does the black dot mean?

Multiplication

[JennyZhu1K]

This was extremely helpful thank you!

[Misha_Khan_2H]

Fe2O3dot3H2O is a single compound. You just need to put 2 in front of Fe2O3 and it will also apply to 3H2O.
I did the mistake of putting brackets around Fe2O3dot3H2O, which was also incorrect. Just writing 2 in front of Fe2O3 is enough for balancing the compound.

[Ally M]

thanks for the answers!
I get that it's a single compound and that it would apply to the whole thing, but why does it make a difference with/without the brackets?

[RalphGuevarra]

Thank you so much for the answer! This is extremely helpful!

[Deivy Gonzalez 3H]

I'm glad you guys help in the post. I could not figure out my error until I realized I accidently forgot to put a coefficient for H20. Thank you.

[AChassion Dis2A]

Hey!

You have everything right, just remember that because H2O is multiplied by the Fe2O3, the coefficient for the Iron (III) Oxide also applies to the H2O. You did really well on this hard problem!

[bella moore]

Wow, thank you for this answer! I didn't know that the 3 in the product applied to the entire molecule so I didn't have 6H2Os in my reactant and I kept getting it wrong, but that makes a lot of sense!

[Mari Brielle Mailed 1B]

Like everyone else mentioned, you balanced the entire equation correctly, except that you applied the coefficient of 2 to Fe₂O₃∙3H₂O(s) twice because you wrote 2Fe₂O₃∙6H₂O(s)! The dot in between Fe₂O₃ and 3H₂O(s) indicates that this species is considered a single unit/compound; they aren't separate.

In case anyone else is confused to how to get to the final product, here's a walk-through of how to get the solution:

1. Write the unbalanced chemical equation.

The problem says "Rust is caused by iron reacting with oxygen gas in the presence of water...Red rust is caused by the formation of iron(III) oxide trihydrate (Fe₂O₃∙3H₂O(s))"

Therefore,
Reactants are: Fe(s), O₂ (g), and H₂O (l)
Product is: Fe₂O₃∙3H₂O(s)

The unbalanced chemical equation is:
Fe(s)+O₂(g)+H₂O(l)⟶Fe₂O₃∙3H₂O

2. Balance the Fe atoms.

There is one Fe atom on the left (reactants) and 2 Fe atoms on the right (products), so add a coefficient of 2 to Fe(s) to yield 2Fe(s)
Currently the equation looks like: 2Fe(s)+O₂(g)+H₂O(l)⟶Fe₂O₃∙3H₂O

3. Balance the H₂O molecules.

Since the product treats H₂O like a unit, we can also treat it as a whole entity while balancing the equation. Thus, we can add the coefficient 3 to H₂O in the reactants to balance the 3H₂O in the products.
Now, the equation looks like: 2Fe(s)+O₂(g)+3H₂O(l)⟶Fe₂O₃∙3H₂O

4. Balance the O atoms.

Currently there are 2 oxygen atoms on the left and 3 oxygen atoms on the right. This means that there is a ratio of 2:3, and adding a coefficient of 3/2 to O₂ will consequently balance the number of oxygen atoms in the reactants and products.
After this step, the equation looks like: 2Fe(s)+3/2O₂(g)+3H₂O(l)⟶Fe₂O₃∙3H₂O

5. Get rid of the fraction coefficients.

Everything is now balanced, but to make the reaction cleaner, we can multiply the entire reaction by 2 to remove the fraction coefficients.

This gives us a final answer of 4Fe(s)+3O₂(g)+6H₂O(l)⟶2Fe₂O₃∙3H₂O

Checking Work:
Reactants:
Fe: 4
O: 6
H₂O: 6

Products:
Fe: 4
O: 6
H₂O: 6

Atoms in Reactants = Atoms in Products

[Jacqueline_Velasquez_14B]

Hi! I hope my explanation helps!

1. Start by writing the reactants on the left side of the arrow and the products on the right side.

Fe(s)+O2(g)+H2O(l)⟶Fe2O3∙3H2O(s)

2. Balance the Fe atoms by placing the coefficient 2 in front of Fe.

2Fe(s)+O2(g)+H2O(l)⟶Fe2O3∙3H2O(s)

3. Balance the H2O molecules as a unit by adding the coefficient 3 to H2O

2Fe(s)+O2(g)+3H2O(l)⟶Fe2O3∙3H2O(s)

4. Oxygen is more difficult to balance. There are two O atoms on the reactant side, and three O atoms on the product side. To balance the O atoms, the coefficient for O2
must be 3/2

2Fe(s)+3/2O2(g)+3H2O(l)⟶Fe2O3∙3H2O(s)

5. Double all of the coefficients to get rid of the fraction. And there is your answer!

4Fe(s)+3O2(g)+6H2O(l)⟶2Fe2O3∙3H2O(s)

[Anabelle Pham 2C]

I think that the 6H20 should be 3H20 instead. First I put the reactants on the left and got: Fe(s)+O2(g)+H2O(l)⟶Fe2O3∙3H2O(s). Then, I balanced Fe and got: 2Fe(s)+O2(g)+H2O(l)⟶Fe2O3∙3H2O(s). Next, I balanced the H20 and got: 2Fe(s)+O2(g)+3H2O(l)⟶Fe2O3∙3H2O(s). Then, I balanced the O: 2Fe(s)+3/2O2(g)+3H2O(l)⟶Fe2O3∙3H2O(s). So, the answer should be: 4Fe(s)+3O2(g)+6H2O(l)⟶2Fe2O3∙3H2O(s)