Observation: I am in the lab timing how long it takes to boil 100 mL of water in a beaker over a Bunsen burner. I observe it takes 5:15 mins to boil the water. I want to get the most accurate answer possible so I repeat the test again making sure everything is the same. This time it takes 7:05 mins to boil the water. I think this is unusual so I repeat the experiment a third time and it takes 5:20 mins. What could we infer about the differences in the times observed?

We can infer that the observed time differences may be the result of impurities present in the water.

We can achieve this result because:

However, the boiling temperature of water (100°C) can be changed if the water contains any kind of impurity. In this case, we can infer that the second experiment of the student contained impure water, which made the boiling temperature higher.

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The likely causes inferred about the differences in times observed are;

1) Slight increase of the vapor pressure of the air immediately above the water surface due to the presence of a lid

2) Variation of heat input due to wind draft that alters the focus of the flame

3) The introduction of impurities into the water from the water source or through the sourcing mediums or containers or during handling of the water

Explanation:

The factors that affect the boiling point of water includes;

1) The amount of heat supplied, to the water

2) Vapor pressure above the water surface

3) Presence of impurities in the water

Therefore, the most likely causes for the difference in the times observed for the water to boil in the order of increasing probability of cause and effect are therefore;

1) Slight increase of the vapor pressure of the air immediately above the water surface due to the presence of a lid

2) Variation of heat input due to wind draft that alters the focus of the flame

3) The introduction of impurities into the water from the water source or through the sourcing mediums or containers or during handling of the water.