How much heat in kilojoules must be removed from a glass of water that contains 100g of water to lower its temperature from 30 C to 15 C?
q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
To calculate the amount of heat that needs to be removed from the glass of water, we can use the formula:
Q = m * c * ΔT
Where:
Q = Amount of heat transferred (in joules)
m = Mass of the water (in kilograms)
c = Specific heat capacity of water (in joules per gram per degree Celsius)
ΔT = Change in temperature (in degrees Celsius)
First, let's convert the mass of water from grams to kilograms:
m = 100 g = 0.1 kg
Next, we need to determine the specific heat capacity of water. The specific heat capacity of water is approximately 4.18 joules per gram per degree Celsius.
Now, we can calculate the amount of heat transferred:
Q = 0.1 kg * 4.18 J/g°C * (15°C - 30°C)
Q = 0.1 kg * 4.18 J/g°C * (-15°C)
Q = -0.627 J
Since the result is in joules, we can convert it to kilojoules by dividing by 1000:
Q = -0.627 J / 1000 = -0.000627 kJ
Therefore, approximately 0.000627 kilojoules of heat must be removed from the glass of water to lower its temperature from 30°C to 15°C.
To find the amount of heat that must be removed from the glass of water, you can use the formula:
Q = m * c * ΔT
Where:
Q is the heat energy in joules
m is the mass of the substance in kilograms
c is the specific heat capacity of water (approximately 4.186 J/g°C or 4.186 kJ/kg°C)
ΔT is the change in temperature in degrees Celsius
First, convert the mass of water from grams to kilograms:
m = 100g ÷ 1000 = 0.1 kg
Next, calculate the change in temperature:
ΔT = 30°C - 15°C = 15°C
Now, substitute the values into the formula and solve for Q:
Q = 0.1 kg * 4.186 kJ/kg°C * 15°C
Q = 0.6279 kJ
Therefore, approximately 0.628 kilojoules of heat must be removed from the glass of water to lower its temperature from 30°C to 15°C.