| How Much Water is in a carrot? |  |
Introduction:
Life exists on Earth because of the abundance of liquid water. Water makes up anywhere from 70 to 90% of the body weight of living things. Living things are composed of atoms and molecules within aqueous solutions (solutions that have materials dissolved in water). At most temperatures on the surface of the earth, water is a liquid. In this state, water is an excellent solvent, and because there is so much of it available on the earth’s surface, water is home (oceans, lakes and rivers) to much of life. Water has been referred to as the universal solvent. Water is also involved in many metabolic processes within organisms.
Water is a polar molecule and can bond both to itself and to other water molecules by weak attractions called hydrogen bonds. Hydrogen bonding is responsible for the unusual thermal properties of water including a high specific heat capacity and a high heat of vaporization.
Specific heat is defined as the amount of heat energy needed to raise the temperature of one gram of a substance 1°C. Since it takes much more energy that normal to break all the hydrogen bonds in liquid water, water resists rapid temperature fluctuations, adding stability to earth’s environments where liquid water is plentiful.
The heat of vaporization is defined as the energy needed to change the phase of a liquid to a gas. Again, because of the number and relative strength of water’s hydrogen bonds, it takes a great deal of energy to break a molecule free of its liquid partners. Heat of vaporization causes a cooling effect because as the warmer molecules evaporate from your skin they take the heat energy with them, leaving you cooler.
Objective:
Students will design and conduct an experiment to determine the amount of water present in a carrot.
Materials:
Some materials that will be available for you to use are plates, vegetable peelers, knives, graters, knee-hi stockings, foil, microwave, blow dryers, plastic bags, and paper towels. Any other materials you use must be approved by the teacher first (No dehydrators!).
Procedure:
- Begin by weighing and recording the mass of the carrot.
- Estimate the water content present in your carrot.
- Develop a hypothesis for the amount of water in a carrot.
- Write the materials needed and procedure you will be using to extract the water.
- After having your hypothesis and procedure approved by the teacher, conduct the experiment.
- Be sure to include an introduction, procedure, data, data analysis, and a conclusion in your lab report.
