# Specific heat ratios of water, air, and related questions

• sempiris
In summary, the speaker is struggling to find heat capacity values/heat capacity ratios for their research project. They have obtained values of 1.33 for the gamma value of steam and 1.4 for air at 300K, but are seeking confirmation. They also have a question about finding the heat capacity ratio for a sample of humid water, and are wondering if they should average the heat capacity ratios for steam and air based on their percentage of mass in the sample. They are advised to consult a thermodynamics book for the Cp and Cv values of gases at different temperatures and pressures.
sempiris
I've been working on a research project and I'm having difficulty with finding heat capacity values/heat capacity ratios. I have been getting 1.33 for the gamma value of steam, and 1.4 for air (at 300K). I was hoping someone could confirm these values.

also, I have a question...let's say we have a sample of humid water, and i need to find the heat capacity ratio for that sample: would I do it by averaging the heat capacity ratios for steam and air relative to their % mass in the sample?

The Cp and Cv values of gases should be given in the back of any thermodynamics book for various temperatures and pressures.

I can confirm that the specific heat ratio (gamma) for steam is typically around 1.33 and for air at 300K is 1.4. These values may vary slightly depending on the pressure and temperature conditions, but they are generally accepted values for these substances.

Regarding your question about finding the heat capacity ratio for a sample of humid water, it is important to consider that the heat capacity ratio is a property of a substance, not a mixture. Therefore, it would not be appropriate to average the heat capacity ratios for steam and air based on their percentage mass in the sample. Instead, you would need to calculate the specific heat ratio for the humid water based on its own unique properties, taking into account the amount of water vapor present and its effect on the overall heat capacity of the sample. This can be a complex calculation, but there are resources available that can help guide you through it.

## 1. What is specific heat and why is it important?

Specific heat refers to the amount of energy required to raise the temperature of a substance by a certain amount. It is important because it helps us understand how different substances react to changes in temperature and how much energy is needed to heat or cool them.

## 2. What is the specific heat ratio of water?

The specific heat ratio of water is 4.18 joules/gram °C. This means that it takes 4.18 joules of energy to raise the temperature of 1 gram of water by 1 degree Celsius.

## 3. How does the specific heat of water compare to air?

The specific heat of water is significantly higher than air, as air has a specific heat ratio of approximately 1 joule/gram °C. This means that it takes much less energy to raise the temperature of air compared to water.

## 4. Why does water have a higher specific heat than air?

This is due to the molecular structure of water, which allows it to absorb and retain more heat energy compared to the molecules in air. Water molecules are more tightly bound together, making it harder to change their temperature compared to the more loosely bound molecules in air.

## 5. How does the specific heat of water affect the Earth's climate?

The high specific heat of water plays a crucial role in regulating the Earth's climate. The oceans act as a heat sink, absorbing and storing large amounts of heat energy from the sun and releasing it slowly over time. This helps to moderate the Earth's temperature and prevent extreme fluctuations that could be harmful to life on our planet.

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