When carbon is burned in air, it reacts with oxygen to form carbon dioxide. when 20.4 g of carbon were burned in the presence of 66.2 g of oxygen, 11.8 g of oxygen remained unreacted. what mass of carbon dioxide was produced?

74.77 g

The equation for the reaction between carbon and Oxygen is given by;

C(s) + O₂(g) → CO₂(g)

We are given;

Mass of carbon 20.4 g

Mass of Oxygen is 66.2 g

Remaining mass of Oxygen after the reaction is 11.8 g

Therefore, Carbon is the rate limiting reagent since Oxygen was in excess.

We are required to calculate the mass of carbon dioxide produced.

Moles = Mass ÷ Molar mass

Molar mass of carbon = 12.01 g/mol

Therefore;

Moles of Carbon = 20.4 g ÷ 12.01 g/mol

                           = 1.699 moles

From the equation, 1 mole of carbon reacts to produce 1 mole of carbon dioxide.

Therefore, the mole ratio of Carbon to carbon dioxide is 1 :1

Thus, moles of carbon dioxide = Moles of carbon

                                                  = 1.699 moles

Mass = Moles × Molar mass

Molar mass of carbon dioxide = 44.01 g/mol

Therefore;

Mass = 1.699 moles × 44.01 g/mol

         = 74.77 g

Therefore, the mass of carbon dioxide gas produced is 74.77 g

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

thats a little if u want the answer just look it up on google thats what i do haha : )