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“Acids, Bases, and Salts”: 

“ Acids, Bases, and Salts ” Aneesh Attri 10 th B Science

Reactions with indicators: 

Reactions with indicators Indicator Acid color Neutral color Base color Phenolphthalein Colorless Faint pink Dark pink Bromthymol blue Yellow Green Blue Litmus Red ----- Blue

Acids: 

Acids Is any compound that increases the number of hydronium ions when dissolved in water. Acid has a sour flavor. Acids change colors in indicators. Blue litmus to red. Acids reacts with metals to produce hydrogen gas. Acids conduct an electric current Examples: Lemon makes your iced tea lighter.

Weak vs. Strong Acids: 

Weak vs. Strong Acids Weak Acids do not ionize completely: Acetic, Boric, Nitrous, Phosphoric, Sulfurous Strong Acids ionize completely: Hydrochloric, Nitric; Sulfuric, Hydriodic

Common Acids : 

Common Acids HCl- hydrochloric- stomach acid H 2 SO 4 - sulfuric acid - car batteries HNO 3 – nitric acid - explosives HC 2 H 3 O 2 - acetic acid - vinegar H 2 CO 3 -carbonic acid – sodas H 3 PO 4 - phosphoric acid -flavorings

Properties of Acids: 

Properties of Acids They taste sour (don’t try this at home). They can conduct electricity . Can be strong or weak electrolytes in aqueous solution React with metals to form H 2 gas. Change the color of indicators (for example: blue litmus turns to red). React with bases (metallic hydroxides) to form water and a salt.

Properties of Acids: 

Properties of Acids They have a pH of less than 7 (more on this concept of pH in a later lesson) They react with carbonates and bicarbonates to produce a salt, water, and carbon dioxide gas How do you know if a chemical is an acid? It usually starts with Hydrogen. H Cl, H 2 SO 4 , H NO 3 , etc. (but not water!)

Acids Affect Indicators, by changing their color: 

Acids Affect Indicators, by changing their color Blue litmus paper turns red in contact with an acid (and red paper stays red).

Acids have a pH less than 7: 

Acids have a pH less than 7

Acids React with Metals: 

Acids React with Metals Acids react with active metals to form salts and hydrogen gas: HCl (aq) + Mg (s) → MgCl 2(aq) + H 2(g) This is a single-replacement reaction

Acids React with Bicarbonates: 

Acids React with Bicarbonates HCl + NaHCO 3 NaCl + H 2 O + CO 2 Hydrochloric acid + sodium bicarbonate salt + water + carbon dioxide An old-time home remedy for relieving an upset stomach

Acids Neutralize Bases: 

Acids Neutralize Bases HCl + NaOH → NaCl + H 2 O - Neutralization reactions ALWAYS produce a salt (which is an ionic compound ) and water. -Of course, it takes the right proportion of acid and base to produce a neutral salt

Bases: 

Bases Is any compound that increases the number of hydroxide ions when dissolved in water. Bases have a bitter flavor and feel slippery. Bases change color in indicators. Red litmus to blue Bases conduct electric currents. Uses of Bases: Sodium Hydroxide is a base used to make soap and paper.

Weak vs. Strong Bases: 

Weak vs. Strong Bases Weak Bases: ammonia; potassium carbonate, sodium carbonate Strong Bases: sodium hydroxide; sodium phosphate; barium hydroxide; calcium hydroxide

Common Bases: 

Common Bases NaOH- sodium hydroxide (LYE) soaps, drain cleaner Mg (OH) 2 - magnesium hydroxide-antacids Al(OH) 3 -aluminum hydroxide-antacids, deodorants NH 4 OH-ammonium hydroxide- “ammonia”

Properties of Bases (metallic hydroxides): 

Properties of Bases (metallic hydroxides) React with acids to form water and a salt. Taste bitter . Feel slippery (don’t try this either). Can be strong or weak electrolytes in aqueous solution Change the color of indicators (red litmus turns blue).

Examples of Bases (metallic hydroxides): 

Examples of Bases (metallic hydroxides) Sodium hydroxide, NaOH ( lye for drain cleaner; soap ) Potassium hydroxide, KOH ( alkaline batteries ) Magnesium hydroxide, Mg(OH) 2 ( Milk of Magnesia ) Calcium hydroxide, Ca(OH) 2 ( lime ; masonry )

Bases Affect Indicators: 

Bases Affect Indicators Red litmus paper turns blue in contact with a base (and blue paper stays blue). Phenolphthalein turns purple in a base.

Bases have a pH greater than 7: 

Bases have a pH greater than 7

Bases Neutralize Acids: 

Bases Neutralize Acids Milk of Magnesia contains magnesium hydroxide, Mg(OH) 2 , which neutralizes stomach acid, HCl. 2 HCl + Mg(OH) 2 MgCl 2 + 2 H 2 O Magnesium salts can cause diarrhea (thus they are used as a laxative) and may also cause kidney stones.

Salts: 

Salts Is an ionic compound formed from the positive ion of a base and the negative ion of an acid. When an acid neutralizes a base a salt is formed. Example: Table salt or sodium chloride.

PowerPoint Presentation: 

End of Chapter 19