Chemical/Physical Properties & pH

7.P.2B.3 Analyze and interpret data to compare the physical properties, chemical properties (neutralization to form a salt, reaction with metals), and pH of various solutions and classify solutions as acids or bases. Physical Properties You should already know that: ● Physical properties can be observed without changing the composition of the substance. Chemical Properties You should already know that: ● Chemical properties can ONLY be observed by changing the composition of the substance, forming new substances. pH Scale

● A tool that is used to measure how acidic or alkaline (basic) something is. ● Measures from 0 to 14. Acids Acidic solutions have a pH between 0 and 6. Chemical formulas usually start with H Examples of acids: Bases Alkaline (basic) solutions have a pH between 8 and 14. Chemical formulas usually end in OH Examples of bases: Neutrals Neutral solutions have a pH of 7. Example of neutral: Chemical Properties of ACIDS ● React with some metals to give off a gas

● Neutralization occurs when acids and bases react with each other. They can form a salt and usually water. Chemical Properties of ACIDS ● React with blue litmus paper turning it red

● Does not react with red litmus paper and the litmus paper will remain red.

● Doesn’t react with phenolphthalein Physical Properties of ACIDS

● Tastes sour

● Sticky texture Chemical Properties of BASES ● Neutralization occurs when bases and acids react with each other. They can form a salt and usually water.

● React with red litmus paper turning it blue. Chemical Properties of BASES ● Does not react with blue litmus paper and the litmus paper will remain red.

● Reacts with phenolphthalein turning it magenta (pink) Physical Properties of BASES

● Tastes bitter

● Slippery texture Chemical Properties of NEUTRALS ● Are formed when neutralization occurs between acids and bases.

● Neither an acid nor a base. Chemical Properties of NEUTRALS ● Reacts with litmus paper turning it violet.

● Reacts with phenolphthalein turning it magenta (pink). Indicators Substances that can be used to determine if a solution is acidic, basic, or neutral. Litmus Paper Phenolphthalein pH Paper Litmus Paper ● Has a special dye on it that changes colors in the presence of an acid or base. ● Blue litmus paper turns red in an acid, and stays blue in a base. ● Red litmus paper turns blue in a base, and stays red in an acid. Phenolphthalein ● Is used to test for the presence of a base.

● It is a colorless chemical that turns magenta (bright pink) in a base, and stays colorless in neutral or acidic solutions. pH paper ● Has a range of colors depending on the pH of the solutions

● The color of the paper is compared to the chart on the vial to determine the pH