Properties of a Candle Flashcards
chemical formula of a candle combustion reaction
wax/C20H42 + O2 = C2 + H2O + CO2
where does the C20H42 come from and why is it necessary in the combustion reaction? (include specific evidence)
reactant - C20H42 is the molecule for wax, which is present in the candle. Without the wax, the wick of the candle burns very quickly, which shows that the wax is a necessary component for fueling the candle. when water droplets are placed between the wick and the wax, the flame extinguishes, proving wax is a necessary component of the combustion reaction. the wax turns ointo liquid and fuels the candle
why is O2 necessary in the combustion reaction? (include specific evidence)
reactant - O2 is present in and necessary for the candle because the flame extinguishes in the absence of oxygen. When a candle is placed inside of a beaker and does not have access to oxygen, the flame extinguishes.
where does C2 come from in the combustion reaction? (provide specific evidence)
product - C2 is evidently a product of the combustion reaction because when the beaker is placed over the candle, it produces a black-colored soot, which is C2. Carbon is also present in the wax (C20H42), therefore it is possible for it to be a product of the reaction
where does H2O come from in the combustion reaction? (provide specific evidence)
product - H2O is evidently a product of the combustion reaction because when a blue piece of cobalt chloride paper was swiped inside the beaker after the candle had been lit in it, the paper turned pink. When tested with several other elements, the cobalt chloride turned pink when in contact with water. Hydrogen is present in the wax (C20H42) and oxygen is another reactant, therefore it is possible for H2O to be a product of the combustion reaction
where does CO2 come from in the combustion reaction?
product - CO2 is evidently a product of the combustion reaction because when an Erlenmeyer flask containing clear lime juice was blown into, the solution turned foggy. Humans breathe out CO2. When the lime water was placed in a flask after a burning candle, a similar reaction happened, and the solution turned foggy. Carbon is present in the wax (C20H42) and oxygen is another necessary reactant, therefore it is possible for CO2 to be a product of the combustion reaction.
when/where is a chemical change happening during the combustion reaction
in the outer yellow region of the candle, the smoke produced is made of carbon, which is a product of the reaction. therefore, a chemical change is happening. therefore heat has been released.
when/where is a physical change happening during the combustion reaction?
in the inner dark region of the candle, the smoke produced is made of wax, which is a reactant or the reaction. Therefore, a physical change is occurring, and the chemical reaction has not yet occurred, thus heat has not yet been released.
what is in the smoke produced by the inner layer of the candle
wax in gas form
which region of the candle is hotter
outer yellow region
what is in the smoke produced by the outer layer of the candle
carbon
which region of the candle is cooler
inner region
