Everyday you encounter a variety of different acids and bases. Below is a list of som common acids and bases

Transcription

1 Acids and Bases Everyday you encounter a variety of different acids and bases. Below is a list of som common acids and bases Milk carbonic acid (H 2 CO 3 ) calcium hydroxide (Ca(OH) s ) sodium hydroxide (NaOH)hydrochloric acid (HCl) Definitions 1) Acid a substance that produces in solution e.g. hydrochloric acid, HCl(aq) dissolves in water to produce H + (aq) and Cl (aq) ions 2) Base a substance that produces in solution e.g. sodium hydroxide, NaOH(aq) dissolves in water to produce Na + (aq) and OH (aq) ions Properties of an Acid Acids have many different properties. Chemists use these to determine the presence an acid in a substance. Reactions with Metal Acids react with metals to produce bubbles of gas. HA + metal ex The gas produced when you react an acid with a metal is. During an experiment you can test for the presence of this gas by using a splint, which causes a. Reaction with Carbonates Acids also react with metal carbonates to produce a different form of gas. HA + metal carbonate ex The gas produced when you react an acid with a carbonate is. You can test for the presences of this gas by using a splint, which causes the. 1

2 More Properties of Acids Electrical Conductivity Many acids are conductors of electricity. In order for a solution of conduct electricity it must contain. When an acid is diluted in water, the water molecules collide with the acid molecules which causes the formation of (H + ) and. This process is called. ex. HCl (aq) H + (aq) + Cl (aq) HA (aq) H + (aq) + A (aq) Reactions with Indicators In this class we will be using three different acid base indicators to test for acids. Phenolphthalein litmus paper bromothymol blue When you put the indicator in the acid, the acid will change colour. turns red in turns colourless in turns yellow in Touch and Taste If you were to spill and acid on an open wound on your skin it would. Stronger acids could burn your skin. Acids taste sour (ex. lemons, grapefruit, spoiled milk). (NOTE: Never taste an acid in a chemistry lab!!) 2

3 Property of Bases Reactions with Metal and Carbonates Unlike acids, bases do not react with metals and carbonates to produce a gas. Electricity Conductor Bases are conductors of electricity. Since many common bases are ionic compounds, when they dissolve in water their are released. ex. NaOH (s) Na + (aq) + OH (aq) Reactions with Indicators When you put an acid base indicator in a base it will change colour turns blue in turns pink in turns blue in Touch and Taste Bases feel on your skin. Bases taste bitter (soap, Brussels sprouts). ph Scale Chemists use a numerical scale to determine how acidic or basic a solution is. The ranges from 0 to 14. A solution with a ph of 7 is, which means that it is not acidic nor basic (the concentration of hydrogen ions equals the concentration of hydroxide ions). has a ph of 7. A solution with a ph less than 7 is considered, which means that there are more ions than ions. A solution with a ph greater than 7 is considered, which means that it has more ions than ions. A solution with a ph closer to 0 is a. A solution with a ph just below 7 is a. A solution with a ph just above 7 is a. A solution with a ph closer to 14 is a. 3

4 Situations where ph is controlled There are many situations in within the environment where ph is controlled. ph in your body Different parts of your body require different ph levels. Your blood has a ph level o, urine has a ph level around, and your skin has a ph around. Your stomach has a ph around. Heartburn occurs when your stomach acid irritates your esophagus. You can use a to treat the heartburn, the most common being an antacid. Swimming Pools If you have a swimming pool you need to check the ph levels often. If your pool is too acidic you have to add a. If your pool is too basic you have to add a. Soil levels Depending on the plant, the ph in the surrounding soil could be acidic or basic. A rapid change in the ph of soil can kill vegetation and plants. Fish Tanks and ponds The ph of fish tanks and ponds should be neutral, or a little basic. A rapid change in ph can cause stress or kill the fish in lakes and streams. If the water drop below neutral it makes the water, which could kill the fish and organisms living in the water. Other Problems with Acids and Bases in the Environment Acid Rain Pollutants in the air (sulfur dioxide, carbon dioxide, nitrogen dioxide) react with water to produce acids SO 2 + H 2 O CO 2 + H 2 O NO 2 + H 2 O 4

5 Neutralization Reaction When an acid reacts with a base it produces a solution with a ph that is closer to 7, which is said to be. We have learned that acids produce ions, and bases produce ions. When you mix and acid and a base together, the ions and ions will react together to produce (we proved this during the neutralization lab by using the strip). The other product is usually an ionic compound, called a. Acid + Base Water + Salt The salt is a neutral substance produced is composed of the ion of the acid and the ion of the base. Prediciting the Properties of a Neutralization reaction A neutralization reaction follows the same formula as a double displacment reaction. From the lab that we did yesterday we know that ex. HCl + NaOH we know NaCl as being. ex. H 2 CO 3 + Al(OH) 3 5