Sapling Q1

[OwenSumter_2F]

So the question on Sapling Q1 is to give the systematic name of this coordination compound: [Co(NH₃)₄Cl²]Cl. I thought the answer was tetra ammine chloro cobalt (II) chloride, but that isn't correct. What part am I doing wrong?

[Breanna Ouyang 1I]

Maybe try typing it differently? I was having a similar problem and if your answer is tetra ammine chloro cobalt (II) chloride, type it in as tetraamminechlorocobalt(II) chloride because the anion is outside and technically separate. It might also be dichloro

[marlene 1K]

I would double check the way you're formatting it. I put it in all as one big word so that might be the problem. Also, double check to make sure you have it all correct in terms I kept using the wrong term for one of the pieces and that was the reason I kept getting it wrong.

[Ven Chavez 2K]

From what you gave it seems like there are three chlorides so maybe the oxidation state of Cobalt is (III) and not (II). So it would be tetraaminechlorocobalt(III) chloride. For example, [Co(NH3)6] Cl3 which is HexaammineCobalt(III) Chloride.

[Kiyoka Kim 3C]

I believe the cobalt has an oxidation state of +3 and not +2 because each Cl has a -1 charge and NH3 is a neutral compound.

[Akshata Kapadne 2K]

I agree with Kiyoka that cobalt should have an oxidation state of +3. Also, since there are 2 chlorines, there should be a prefix, so it would be dichloro instead of just chloro. Once you combine all the terms into one word with a space before chloride, you should be fine.

[505612629]

Hi! I believe Cobalt's charge is 3+ instead of 2+ and spelling errors got me, so be sure you're spelling it right when submitting. Hope this helps!

[jessicasilverstein1F]

I had a similar problem. The cobalt has an oxidation state of +3 and not +2 because each Cl has a -1 charge and NH3 is a neutral compound. It is not +2, but is +3. Hopefully that helps

[Brendan Duong 1I]

I had a similar problem. The cobalt has an oxidation state of +3 and not +2 because each Cl has a -1 charge and NH3 is a neutral compound. It is not +2, but is +3. Hopefully that helps

Why would it be +3? I thought the overall charge of the molecule is neutral so +2 would cancel out the two -1s? I am confused. Is the overall charge not 0? If so, why?

[HannahRobinson3L]

I had a similar problem. The cobalt has an oxidation state of +3 and not +2 because each Cl has a -1 charge and NH3 is a neutral compound. It is not +2, but is +3. Hopefully that helps

Why would it be +3? I thought the overall charge of the molecule is neutral so +2 would cancel out the two -1s? I am confused. Is the overall charge not 0? If so, why?

The overall charge is zero. You have to count the chlorine that is outside of the brackets as well, for a total of three chlorine, each with -1 charge.

[Laura 3l]

From what you gave it seems like there are three chlorides so maybe the oxidation state of Cobalt is (III) and not (II). So it would be tetraaminechlorocobalt(III) chloride. For example, [Co(NH3)6] Cl3 which is HexaammineCobalt(III) Chloride.

I also had an issue with this problem, make sure you use the Roman numeral character in your answer. I put tetraamminechlorocobalt(III)chloride, using "(III)" to represent the Roman numeral three.

[VincentLe_3A]

The charge of the transition metal cobalt would have to be +3 because the overall charge of the coordination compound would have to be +1 in order to compensate for the -1 charge of the chloride anion. Since there are 2 chlorine anions within the coordination compound, the charge of the cobalt would have to +3 to make the overall charge of the coordination compound to be +1. This would correspond to the Roman numeral (III) following the cobalt instead of (II).

[Yashvi Reddy 1H]

Hi! Great question, I also ran into some trouble with this problem. I would try what others have said above, figuring out formatting usually works for me!

[Kat Stahl 2K]

I got the answer Triamminetrichlorocobalt(III). Your oxidation number/charge is off.

[Pranav Daggubati 3C]

It should be cobalt(III), not cobalt(II), which means its tetraamminechlorocobalt(III) chloride

[MichaelMendozaD1F]

so would amine have two m's?

[Jessica Hu 3L]

Not totally related, but for some of those having a problem with answering on sapling, also make sure you don't put spaces. I had tetra-ammine dichloro copper (III) chloride and they didn't take it until I changed it to tetraamminedichloro copper (III) chloride.

[Charmaine Ng 2D]

As others have said already, the oxidation of the Cobalt should be +3, not +2. The entire compound has a neutral charge, and taking the chlorine outside the brackets into consideration, the coordination complex should have an overall +1 charge. This means, within the brackets, Cobalt's charge + (-2) = +1, so Cobalt's charge is +3!

[Brianna Chen 3F]

In this problem, cobalt has an oxidation number of +3 instead of +2. Therefore, the roman numeral next to cobalt should be (III) not (II) because NH3 is neutral and Cl has a -1 charge. Therefore, you want the coordination sphere to have a charge of +1 to cancel out the charge of the outside Cl which is -1. Since inside the brackets has a charge of -2 due to the two Cl atoms, you need cobalt to have an oxidation number of +3 in order to assign a +1 charge overall to the coordination sphere.

[Jonathan Banh 1G]

You are correct in your method of deducing that it was "tetraamine" from (NH3)4. I believe the first mistake made was in not recognizing the number of Cl ligands correctly. As there are two and not just one, the prefix "di" should be attached to the ligand name "chloro" to give a partial section of the coordination compound's name as "dichloro". The second one is because the oxidation state of cobalt is actually +3, and not +2. This is because it must compensate for the three negative charges present from the Cl to make a neutrally charged coordination compound. Thus, the answer you should end up with is tetraamminedichlorocobalt(III) chloride.

[Chudi Onyedika 3A]

You need to factor the chlorine that is outside of the brackets as well when determining the oxidation number for Cobalt.