pH lab - Name LABORATORY ‐ WATER ACIDS BASES pH...

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1 Name ___________________________ LA Purpose/Objectives Identify characteristics of chemicals that make them soluble or insoluble in water. Predict solubility of biologically relevant molecules in water. Identify pH values for acid, neutral, and basic solutions. Use a pH indicator to analyze molecules that are soluble in water to determine if they form an acidic or basic solution. Observe the changes in pH as acid is added to buffered and unbuffered solutions. Measure the pH of solutions using a pH meter. Background On average, living organisms are 70% or more water. Water is life’s essential chemical. Water is required for the basic chemical reactions of life. Some of water’s properties make it ideal for maintaining biological organisms: Water is a liquid at room temperature due to hydrogen‐bond attractions between molecules. Water is a good solvent. It is a polar molecule, which means it has partial positive and negative charges, which can interact with the positive or negative charges on hydrophilic (water loving) chemicals. The molecules that dissolve in water are called “solutes”. Water takes a lot of energy to raise or lower its temperature helping living organisms maintain a more constant temperature. Water can fill vessels and spaces in living organisms and provides lubrication. In this lab you will observe how water interacts with several chemicals. You will observe some chemicals that are soluble (are able to dissolve) in water and other chemicals that are insoluble (unable to dissolve) in water. Some chemicals may fall in‐between or are “partially soluble”.Water‐soluble chemicals are also described as being HYDROPHILIC or water loving; chemicals that are insoluble in water are called HYDROPHOBIC or water fearing. Generally, chemicals that have full or partial charges are hydrophilic or POLAR ; chemicals without any charges are hydrophobic or NONPOLAR . Here is another way to express these ideas: Polar molecules will mix with other polar molecules to form solutions. Nonpolar molecules will mix with other nonpolar molecules to form solutions.
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pH lab - Name LABORATORY ‐ WATER ACIDS BASES pH...

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