Question

Опыт 3 Влияние воздуха на горение свечи Вставьте стеклянную трубку с оттянутым концом в резиновую грушу. Сжимая её рукой, продуйте в пламя горящей свечи воздух. Как изменилась яркость пламе- ни? Прикрепите две свечи при помощи расплавленного парафина к картону (фанере, оргaлиту). Зажгите их и накройте одну поллитровой банкой, другую — двух- литровой (можно взять химические стаканы различ- Ной вместимости). В каком случае свеча горит дольше? Почему? Запишите уравнения реакций горения, если вещест- ва, из которых состоит свеча, имеют формулы С6Н24 и C17H36-

Answer 1

Ответ:

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Answer 2

The Influence of Air on Candle Burning

When air interacts with a burning candle, it plays a crucial role in sustaining the combustion process. By providing oxygen, air enables the candle to continue burning. Additionally, the movement of air can affect the brightness and duration of the flame.

To observe the influence of air on candle burning, you can conduct a simple experiment. Here are the steps:

1. Insert a glass tube with one end sealed into a rubber bulb or squeeze bottle. 2. Light a candle and position it in a stable location. 3. Hold the open end of the glass tube near the flame of the candle. 4. Squeeze the rubber bulb or bottle to blow air into the flame.

By blowing air into the flame, you are increasing the supply of oxygen. This can lead to a brighter flame as the combustion process becomes more efficient. The increased oxygen supply allows for more complete combustion of the candle's fuel, resulting in a higher temperature and brighter flame.

However, it's important to note that blowing air directly onto the flame can also cause the flame to flicker or even extinguish momentarily due to the disturbance of the air flow. Once the air flow stabilizes, the flame should regain its brightness.

Two Candles Covered with Jars

In the second part of the experiment, you are asked to attach two candles to a cardboard or similar material using melted paraffin. One candle is covered with a half-liter jar, while the other is covered with a two-liter jar (or two chemical beakers of different capacities).

When a candle is covered with a jar, it creates a closed environment around the flame. This restricts the flow of air to the flame, reducing the supply of oxygen. As a result, the combustion process becomes less efficient, and the flame may burn dimmer and for a shorter duration compared to the candle that is not covered.

The candle covered with the smaller jar (half-liter) will likely burn for a shorter time compared to the candle covered with the larger jar (two-liter). This is because the smaller jar restricts the airflow more, limiting the oxygen supply to the flame even further.

Equations for Candle Combustion

The composition of a candle can vary, but typically it consists of hydrocarbons. Two common hydrocarbons found in candles are C6H14 (hexane) and C17H36 (heptadecane).

The balanced chemical equation for the combustion of hexane (C6H14) can be represented as:

C6H14 + 9O2 → 6CO2 + 7H2O

The balanced chemical equation for the combustion of heptadecane (C17H36) can be represented as:

C17H36 + 25O2 → 17CO2 + 18H2O

These equations show the reaction between the hydrocarbon fuel and oxygen in the air, resulting in the production of carbon dioxide (CO2) and water (H2O) as byproducts of combustion.

It's important to note that the actual composition of a candle may vary depending on the specific materials used. However, the general principle of combustion and the role of air in sustaining the flame remain the same.

Please let me know if there is anything else I can help you with!