Ok, in my lab, I measured the freezing point of NaNO3 and it was 0.79 C
and I have to answer the question:
Why might your measured value of the freezing point of water not equal 0oC?
Elements in the lab that may have changed the outcome.
You could have read the temperature incorrectly.
The measuring device was defective.
Other tutors may have other suggestions.
I have an idea that the question was supposed to have you answer why the f.p. was lower than 0oC and the answer would have been that it was a NaNO3 solution; BUT, I don't know that there is a valid chemical reason for it being higher.
The freezing point of water is commonly known to be 0°C. However, there are several factors that can cause the measured value of the freezing point of water to deviate from this standard value.
Here are some possible reasons why your measured value of the freezing point of water might not equal 0°C:
1. Impurities: Water can contain impurities such as dissolved salts, minerals, gases, or other substances. These impurities lower the freezing point of water, resulting in a measured value that is lower than 0°C. For example, the presence of NaNO3 (sodium nitrate) in your lab sample could have affected the freezing point of water.
2. Pressure: The freezing point of water is influenced by pressure. Under normal atmospheric pressure, water freezes at 0°C. However, as pressure increases, the freezing point decreases. Conversely, as pressure decreases (such as at higher altitudes), the freezing point increases. If your lab experiment was conducted at a different pressure than the standard atmospheric pressure, it could have affected the measured freezing point of water.
3. Supercooling: Supercooling occurs when a liquid is cooled below its freezing point without solidifying. It can happen if there are no impurities or nucleation sites present to initiate ice crystal formation. In such cases, the measured freezing point might be slightly lower than 0°C until a disturbance triggers the freezing process.
To determine the exact reason why your measured value of the freezing point of water deviated from 0°C, it would be helpful to consider the experimental conditions, sample composition, and potential sources of impurities or variations in pressure. Additionally, it is important to ensure that your measurements are accurate and precise by using calibrated equipment and following proper experimental procedures.