Can specific heat be negative? I know energy can be (as in joules or calories) because when something cools down the temperature difference is a negative, and because the energy is an important part of the formula for specific heat, couldn't it be negative?
Specific heat content is defined as the heat required to raise a given mass 1 deg C. It takes real heat (+) to increase temperature, in accordance with the Kinetic Molecular theory.
Then how come calories and joules (as in energy) can be negative?
We learned this formula for cp.
cp of object 2=m(water) * temp. difference (water) * cp (water)% m (object 2) * temp. difference (object 2)
What if the temperature difference is negative for either the water or the object? Wouldn't the cp come out negative?
That is not the definition of specific heat capacity. This formula is exactly wrong. Let me show you.
In any reaction, the sum of the heat gains is zero. Some will lose heat (negative gain), and some will gain.
Heatgainedbywater+ heatgainedbyboject=0
Now if you solve this, it is always correct. Your teacher probably did the old (wrong) Heat gained= heat lost
But this is NOT right what is right is
absolutevalue Heatgained=absolutevalue Heat lost. When you solve it for cp, you get your formula, but you dropped the absolute values signs, making the problem you suggest: how to handle signs.
Heat capacity is always positive.
Thanks, but I should probably do it the way my teacher taught me to. And I guess I'll just drop the negative.
That is fine. Just remember that the heat capacity is always positive, and that the heat gained and lost must add up to zero.
It's understandable that you want to follow the method your teacher taught you. However, it's important to note that understanding the underlying concepts can help you grasp the topic more fully.
In the formula you mentioned, the negative sign could be a result of a temperature difference being negative. However, when it comes to specific heat capacity (cp), it is always defined as a positive value.
If you encounter a negative temperature difference, you should include the absolute value of the difference in your calculations. This ensures that the specific heat capacity remains positive. By dropping the negative sign, you are effectively considering the absolute value of the temperature difference.
So, to summarize, while specific heat capacity (cp) is always positive, you can handle negative temperature differences by taking their absolute values. This way, you can still use the formula your teacher taught you while maintaining the correct sign convention for specific heat capacity.
I understand that you want to follow the method taught by your teacher. However, it is important to note that the correct definition of specific heat capacity does not involve negative values. The specific heat capacity of a substance is always positive because it represents the amount of heat energy required to raise the temperature of a substance by 1 degree Celsius.
If you encounter a situation where the temperature difference is negative for either the water or the object, it does not change the sign of the specific heat capacity. Instead, it would indicate that heat is being transferred from that substance to another, resulting in a decrease in temperature.
I would recommend discussing this topic further with your teacher to clarify any confusion and ensure that you have a correct understanding of specific heat capacity.