what is the number of calories of heat energy released when 25 grams of water is cooled from 20 C to 10 C?

q = mass water x specific heat water x delta T.

250

To calculate the number of calories of heat energy released when water is cooled, you'll need to use the specific heat capacity of water and the equation:

Q = m * c * ΔT

Where:
Q is the heat energy released (in calories)
m is the mass of the water (in grams)
c is the specific heat capacity of water (in calories/gram · °C)
ΔT is the change in temperature (in °C)

First, let's find the specific heat capacity of water. The specific heat capacity of water is approximately 1 calorie/gram · °C.

Next, substitute the given values into the equation:
m = 25 grams (given)
c = 1 calorie/gram · °C (specific heat capacity of water)
ΔT = (final temperature - initial temperature) = (10°C - 20°C) = -10°C

Now, plug in the values:
Q = 25 grams * 1 calorie/gram · °C * -10°C
Q = -250 calories

Therefore, when 25 grams of water is cooled from 20°C to 10°C, approximately 250 calories of heat energy are released.