In the combustion of octane, how many grams of oxygen are needed to completely react and produce 84.00 grams of carbon dioxide?

95.4g

Explanation:

Given parameters:

Mass of carbon dioxide = 84g

Unknown:

Mass of oxygen = ?

Solution:

To solve this problem, we will simply work backward from the known to the unknown specie.

We first must write the balanced equation of the reaction;

             2C₈H₁₈   +    25O₂      →       16CO₂     +      18H₂O

Now, convert the mass of CO₂ to number of moles;

         Number of moles  =

              Molar mass of CO₂ = 12 + 2(16) = 44g/mol

        Number of moles  =   = 1.91moles

From the balanced equation,

                   16 moles of CO₂ is produced by 25 moles of O₂

                   1.91 mole of CO₂ will be produced by   = 2.98mole of O₂

Now, we convert this moles of Oxygen gas to mass;

     Mass of O₂  = number of moles x molar mass

                           = 2.98 x 2(16)

                            = 95.4g

b. atoms in metallic solids are not arranged in a regular pattern

explanation:

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.