EXPT # 4: Determining the amount of heat absorbed by fresh water
Student Name: _________________________________ ___________________________
Introduction:
The specific heat of water is the amount of heat needed to raise the temperature of 1gram of water by by 1°C. One of water’s most significant properties is that it takes a lot of heat for it to make it get hot. Precisely, water has to absorb 4.184 Joules of heat for the temperature of one gram of water to increase by 1 degree celsius (°C). Therefore, water has a specific heat capacity of 4.184 J/g.oC. For comparison sake, it only takes 0.385 Joules of heat to raise the temperature of 1 gram of copper by 1°C, hence the specific heat capacity of copper is 0.385 J/g.oC. Water has a high specific heat index—it absorbs a lot of heat before it begins to get hot. This is why water is valuable to industries and in your car’s radiator as a coolant. The high specific heat index of water also helps regulate the rate at which air changes temperature, which is why the temperature change between seasons is gradual rather than sudden, especially near the oceans. The specific heat capacity therefore is an intrinsic characteristic of matter and different substances can be identified on basis of their specific heat capacity.
The specific heat capacity, C and the amount of heat that any matter can absorb are related by the equation below.
Q = m x C DT ………………………………equation 1
whereby: Q = heat in Joules (J); m = mass in grams (g), C = specific heat capacity in J/g.oC, and
DT = temperature change, (T2-T1) in oC.
Purpose: The purpose of this lab is to determine how much heat is absorbed by certain amount of water if it is heated from T1 to T2. Since the specific heat capacity, C of water is known, for a certain amount of water we can figure out how much heat it absorbs using equation 1.
Materials: (Use household or buy cheaper ones from local store)
Simple Thermometers calibrated in oC.
A graduated cup (in mL)
Microwave
Procedure:
- Using your graduated cup measure about 100 mL of fresh water into a Styrofoam cup.
- Using your thermometer, record temperature of 100 mL of fresh water in the Styrofoam cup before boiling, T1.
- Use the microwave to heat the 100 mL of fresh water in Styrofoam for 2 minutes.
- After 2 minutes, remove the water from the microwave and record the temperature of water, T2.
Post lab Calculations:
- If the density of fresh water is 1.00g/mL, calculate the mass of the water used in this experiment (show calculations).
- The initial temperature of water before heating, T1 =____________oC
iii. The final temperature of water after heating, T2 = ______________ oC
- Calculate the temperature change(∆T) after heating the water for 2 minutes?
- If the specific heat of water is 4.184 J/g*oC, calculate the heat gained by the water after heating for 2 minutes?
- A 3.25g peace of Aluminum metal absorbed 220J of energy and raised its temperature by 72.0 oC. Calculate the specific heat capacity of Aluminum in J/g*oC?
vii. Calculate the % error associated with the specific heat capacity of aluminum metal in (vi) above, if the actual specific heat capacity of aluminum is .902 J/g*oC?
% error = ((Experimental value-Actual value)/Actual value))* 100