How to find the Oxidation Number for Cr in CaCr2O7 (Calcium dichromate)
To find the correct oxidation state of Cr in CaCr2O7 (Calcium dichromate), and each element in the compound, we use a few rules and some simple math. First, since the CaCr2O7 doesn’t have an overall charge (like NO3- or H3O+) we could say that the total of the oxidation numbers for CaCr2O7 will be zero since it is a neutral compound. We write the oxidation number (O.N.) for elements that we know and use these to figure out oxidation number for Cr. --------- RESOURCES How to Find Oxidation Numbers (rules and examples): https://youtu.be/iSAwDJTLIKY Oxidation Numbers Practice: https://youtu.be/hTjSNTOUcBQ ---------- GENERAL RULES Free elements have an oxidation state of zero (e.g. Na, Fe, H2, O2, S8). In an ion the all Oxidation numbers must add up to the charge on the ion. In a neutral compound all Oxidation Numbers must add up to zero. Group 1 = +1 Group 2 = +2 Hydrogen with Non-Metals = +1 Hydrogen with Metals (or Boron) = -1 Fluorine = -1 Oxygen = -2 (except in H2O2 or with Fluorine) Group 17(7A) = -1 except with Oxygen and other halogens lower in the group ---------- We know that Oxygen usually is -2 with a few exceptions. When Oxygen is in a peroxide, like H2O2 (Hydrogen peroxide), it has a charge of -1. When it is bonded to Fluorine (F) it has an oxidation number of +1. Here it is bonded to element symbol so the oxidation number on Oxygen is -2. Using this information we can figure out the oxidation number for the element Cr in CaCr2O7.
To find the correct oxidation state of Cr in CaCr2O7 (Calcium dichromate), and each element in the compound, we use a few rules and some simple math. First, since the CaCr2O7 doesn’t have an overall charge (like NO3- or H3O+) we could say that the total of the oxidation numbers for CaCr2O7 will be zero since it is a neutral compound. We write the oxidation number (O.N.) for elements that we know and use these to figure out oxidation number for Cr. --------- RESOURCES How to Find Oxidation Numbers (rules and examples): https://youtu.be/iSAwDJTLIKY Oxidation Numbers Practice: https://youtu.be/hTjSNTOUcBQ ---------- GENERAL RULES Free elements have an oxidation state of zero (e.g. Na, Fe, H2, O2, S8). In an ion the all Oxidation numbers must add up to the charge on the ion. In a neutral compound all Oxidation Numbers must add up to zero. Group 1 = +1 Group 2 = +2 Hydrogen with Non-Metals = +1 Hydrogen with Metals (or Boron) = -1 Fluorine = -1 Oxygen = -2 (except in H2O2 or with Fluorine) Group 17(7A) = -1 except with Oxygen and other halogens lower in the group ---------- We know that Oxygen usually is -2 with a few exceptions. When Oxygen is in a peroxide, like H2O2 (Hydrogen peroxide), it has a charge of -1. When it is bonded to Fluorine (F) it has an oxidation number of +1. Here it is bonded to element symbol so the oxidation number on Oxygen is -2. Using this information we can figure out the oxidation number for the element Cr in CaCr2O7.