Calculate the number of grams of oxygen required to convert 43.0 g of glucose to CO2 and H2O. mass of O2: TOOLS x10y g Calculate the number of grams of CO2 produced. mass of CO2: g

Answer 1

Hi Jaylin,

The first thing you have to do with this question is write the equation for the reaction so that you can figure out the molar ratios. Anytime you are asked a question about limiting reagents and/or converting between different chemicals in a reaction (like this problem) you will need to start with a properly balanced equation.

This particular case is the combustion reaction. Combustion is a common reaction to get question about because it is a fundamental equation describing what happens when organic material is burned (gasoline in cars, candle wax burning, etc..). There are different types of combustion reactions, but in chemistry courses a full combustion to CO₂ and H₂O is usually assumed.

In this problem you have to know the above information as well as the chemical formula for glucose: C₆H₁₂O₆

Here is the basic combustion reaction (unbalanced):

C₆H₁₂O₆ + O₂ → CO₂ + H₂O

Now we need to balance the equation:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

(Note that in other combustion equations you might not be burning glucose - so the balancing would work out differently with different amounts of carbon, hydrogen, and oxygen in the starting fuel (glucose in this case is the fuel))

We are ready to start building the conversion from mass of glucose to mass of other compounds in this reaction:

43.0 g glucose * (1 mol glucose/180.156 g glucose) * (6 mol O₂/1 mol glucose) * (31.999 g O₂/ 1 mol O₂)

Mass of O₂ = 8.064 g O₂ = 8.06 g O₂

Now we need to calculate the mass of CO₂ - and you can take the same approach:

43.0 g glucose * (1 mol glucose/180.156 g glucose) * (6 mol CO₂/1 mol glucose) * (44.01 g CO₂/ 1 mol CO₂)

Mass of CO₂ = 11.81964 g CO₂ = 11.8 g CO₂

Note that in order to get the conversions between the mass of chemicals and the number of chemicals (mol) you need to use the molar mass. You would get the molar mass from the chemical formula and the periodic table of elements (atomic mass of each element).

Bonus Related Question: What mass of H₂O would you produce in this reaction?

Please set up a session with me if you want to go over this answer in detail or work on other chemical problems!

Best,

Kevin