Ethyl chloride (C₂H₅Cl) boils at 12 °C. When liquid C₂H₅Cl under pressure is sprayed on a room-temperature (25 °C) surface in air, the surface is cooled considerably. (a) What does this observation tell us about the specific heat of C₂H₅Cl(g) as compared with that of C₂H₅Cl(l)?

Video transcript

Welcome back everyone in this example, we're told that the boiling point of a sample is 16 degrees Celsius. A room temperature surface is significantly cooled when the liquid form of the sample under pressure is sprayed on it. So our sample here is a gas at this point and we need to determine which of the below statement is true based on the given info. So all of the answer choices are discussing specific heat. So we should recall our definition for specific heat and we should recall the specific heat is represented by the sea symbol here and its definition is the amount of heat that is required to raise the temperature of a substance By one unit or by 1°C. Now, according to the prompt, our sample or the boiling point of our sample is less than room temperature and our sample vaporizes as it touches the surface. And so that's why the prompt mentions that it's under pressure meaning our sample is going to be in a gas phase as it touches the surface. The prompt also mentions that the surface is cooled when this gaseous form of our sample is sprayed on it and so we can note that heat is transferred from our surface to our sample and that's why the surface is therefore cooler. And so what that means is that the heat content of our gaseous sample is greater than the heat content of our liquid sample. So when the sample is still a liquid, it has a lower heat content. And if on the contrary, our heat content of the gaseous sample is greater than the liquid, that means that we would require a lower specific heat to raise the temperature of this gaseous sample because it's already pretty warm. So that means that we can confirm that the only correct choice to complete this example is going to be choice C. As our final answer, which states that the specific heat of the liquid form is going to be greater than that of the gaseous form due to a lower level of heat content of the liquid, as we stated in our notes. So, C. Is our final answer. I hope that everything I explained was clear because C was the only true statement we've ruled out choices A B and D. Because it doesn't match with the notes that we described below. And if you have any questions, just leave them down below. So I'll see everyone in the next practice video.