Transcript Acids
Describing Matter Key Idea #5 Matter can be described by its physical, chemical, and characteristic properties. What is Matter? Matter is anything that has mass and takes up space. Matter is the “stuff” that makes up everything in the universe. Physical Properties describe the object or substance can be observed or measured without changing the identity of the substance Examples of Physical Properties color odor size shape state (solid, liquid, gas, plasma) texture (smooth, rough, soft, bumpy) density (measured in g/ml and g/cm³) melting point/boiling point/freezing point Three Principle States of Matter Solid Liquid Gas Source: Nasa.gov Chemical Properties are determined by the arrangement of atoms in the molecules making up the object describe a object or substance based on its ability to change into a new substance with different properties cannot be observed with your senses; must be tested aren’t as easy to observe as physical properties Examples of Chemical Properties pH: Flammability Battery acid is 0 Liquid drain cleaner is 14 burning wood forms ash and smoke Reactivity when iron is exposed to moist air, it reacts with oxygen to form rust. Characteristic Properties are most useful in identifying a substance are properties that remain true for any given sample of a substance Examples of Characteristic Properties Boiling point Melting/freezing point Density Chemical Activity of a Substance Another characteristic property is the chemical activity of a substance. Chemical activity is a substance’s ability to undergo a specific chemical change. Example: When wood burns it combines with oxygen in the air to produce ash, smoke, and light (glowing gases). Shared Characteristic Properties Many substances have some of the same characteristic properties as other substances. If you have an unknown clear liquid substance, it is important to study at least two or three characteristic properties before you can accurately identify the substance. Characteristic Properties Substance Boiling Point Melting/Freezing Point Density Pure Water 100°C 0°C 1 g/ml Hydrogen Peroxide 107°C -26°C n/a Rubbing Alcohol 82°C -89°C .786 g/ml pH Scale pH stands for potential of hydrogen. The pH scale ranges from 0 to 14. It measures how acidic or alkaline (basic) a solution is. Googleimages.com A pH of less than 7 means the solution is acidic. A pH of more than 7 means the solution is alkaline (basic). A pH of 7 means it is a neutral solution. Pure water has a pH of 7. The less pH, the more acidic the solution is. The more pH, the more alkaline (basic) the solution is. Googleimages.com Acids and Bases Acids taste sour are corrosive to metals change litmus paper red become less acidic when mixed with bases Bases taste bitter feel slippery change litmus paper blue become less basic when mixed with acids pH Lab You will be working with a partner as you rotate through the stations. You will be using an indicator called a pH test strip to test each substance. Do not touch or taste any of the substances. If you spill something, let me know so I can clean it up. When you finish testing each substance, complete the answers on your lab sheet. pH Lab Procedures Predict whether each substance is an acid or a base. Take turns testing the solutions in the plastic cups by dipping a pH strip into the liquid for about 2 seconds. Take the strip out and "read" the pH within 10 sec. by comparing the color of the strip to the pH color chart. Record the pH on your data chart for each of the numbered solutions. Now determine if the solutions were acids (pH: 0 up to 7), neutral (pH 7) or bases (pH: above 7 to 14) Record this information on your data chart beside each solution. Common Acids Name of Acid Formula Use Acetic CH3COOH Vinegar Carbonic H2CO3 Beverages Hydrochloric HCl Digestion Nitric HNO3 Fertilizer Phosphoric H3PO4 Fertilizer Sulfuric H2SO4 Car Battery Common Bases Name Formula Uses Aluminum Hydroxide Calcium Hydroxide Magnesium Hydroxide Sodium Hydroxide Al(OH)2 Deodorant, antacid Concrete, plaster Antacid, laxative Drain cleaner, soap Ca(OH)2 Mg(OH)2 NaOH The pH of Common Substances Number scale ranges from from 0 - most acidic to 14 - most basic (alkaline). NOTE: pH values may vary between the same types of products because of different growing and processing methods.