Consider the following chemical reaction:
2 c8h18 + 25 o2 > 16 co2 + 18 h2o

what is the mole-to-mole ratio between oxygen gas and water?

25 : 18

Explanation:

Mole ratio:

It is simply the ratio between moles of any two compounds take part in chemical reaction. It gives the proportion of compounds present.

The given reaction is the burning of octane. Two moles of octane burned in the presence of twenty five moles of oxygen and produced sixteen moles of carbon dioxide and eighteen moles of water.

Chemical equation:

C₈H₁₈ + O₂     →     CO₂ +  H₂O

Balance chemical equation:

2C₈H₁₈ + 25O₂     →     16CO₂ + 18H₂O

The mole ratio of oxygen and water is 25 : 18.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

the transfer of heat by electromagnetic radiation is called thermal radiation . it is usually carried out by electromagnetic waves in an energy range just below the visible spectrum, which is the infrared range.

so the answer would be radiation.

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