The number of kilojoules needed to raise the temperature of 125 g of water from 20°C to 95°C is ________. The specific heat of water is 4.184 J/g °C.
125 (95-20)(4.184) Joules
divide by 1000 to get kilojoules
To find the number of kilojoules needed to raise the temperature of 125 g of water from 20°C to 95°C, we can use the formula:
Q = m * c * ΔT
Where:
Q is the heat energy in joules,
m is the mass of the substance in grams,
c is the specific heat capacity of the substance in J/g °C, and
ΔT is the change in temperature in °C.
First, let's calculate the change in temperature:
ΔT = final temperature - initial temperature
ΔT = 95°C - 20°C
ΔT = 75°C
Now, we can substitute the values into the formula:
Q = 125 g * 4.184 J/g °C * 75°C
Calculating:
Q = 392,500 J
To convert from joules to kilojoules, we divide by 1000:
Q = 392,500 J / 1000
Q = 392.5 kJ
Therefore, the number of kilojoules needed to raise the temperature of 125 g of water from 20°C to 95°C is 392.5 kJ.
To find the number of kilojoules needed to raise the temperature of water, we can use the formula:
Q = m * c * ΔT
where:
Q is the amount of heat energy,
m is the mass of the substance (in grams),
c is the specific heat capacity of the substance (in J/g °C),
ΔT is the change in temperature (in °C).
In this case, we need to find the number of kilojoules, so we need to convert the answer to kilojoules.
Given:
m = 125 g (mass of water)
c = 4.184 J/g °C (specific heat of water)
ΔT = (95 - 20) °C (change in temperature)
Let's plug in the values and solve the equation step by step:
Q = 125 g * 4.184 J/g °C * (95 - 20) °C
Q = 125 g * 4.184 J/g °C * 75 °C
Q = 39,275 J (amount of heat energy in joules)
To convert joules to kilojoules, we divide by 1000:
Q = 39,275 J / 1000
Q = 39.275 kJ
Therefore, the number of kilojoules needed to raise the temperature of 125 g of water from 20°C to 95°C is 39.275 kJ.