Lab: Cabbages in Chemistry Telltale Colors 2 points extra credit for printing!  1. In the mixing tray, place 5 drops of the chemical in 12 compartments 2. DIP test the pH paper & record the pH measurement (use the scale on

the bottle) RECORD THIS pH ppr (paper) column below. 3. Place 5 drops of cabbage juice 1 in space 1. What color does it become?

Record in the table below. 4. Complete for the remaining 11 other chemicals. 5. Think about “Alien Juice Bar” virtual lab. Decide whether each chemical

is an acid, base, or neutral. Be sure to COLOR the results. DO NOT Throw these out, but proceed to “Presto Change-o” lab

Product Color Change From Purple

Is it Acid,Base or Neutral?

pH ppr

1. Vinegar Color the result:

2. Baking Soda 3. Water 4. Lemon juice 5. Salt water 6. Drain Cleaner 7. Aspirin/Tonic H2O 8. Alka Seltzer 9. Alcohol 10. Ammonia 11. Sprite 12. Windex Color in the pH scale below, using the colors you obtained above. Then, label: strong acids, strong bases, weak acids, weak bases, neutral.  

   

Presto Change-O You know which colors turned pink, which turned blue/green, but can you make them all pink? Which chemical do you think is the strongest pink? _____________________________________

Which pink chemical will turn a blue/green space pink with the least amount of drops? ________________________________

Test your hypothesis by adding the chemical to each of the “blue/green” spaces. How many drops of pink did it take to turn each “blue/green” space pink? Record your answers & any additional observations: _________________________________________________________________________  ____________________________________________________________________________________________  ____________________________________________________________________________________________  ____________________________________________________________________________________________  ____________________________________________________________________________________________ So, can you do the reverse??? Which chemical do you think is the strongest blue/green? ______________________________

Which blue/green chemical will turn a pink space blue/green with the least amount of drops? _____________________________

Test your hypothesis by adding the chemical to each of the pink spaces. How many drops of blue/green did it take to turn each pink space green? Record your answers & any additional observations: _____________________________________________________________________  _____________________________________________________________________  _____________________________________________________________________  _____________________________________________________________________   Which chemical worked the fastest (least amount of drops), to change a blue/green to pink? ________________

Which worked the fastest to change a pink to blue/green? ________________ Now clean & dry ALL of the wells, and start the next section of testing.

More or Less Acid

Neutralize This! From Base to Neutral 1. Put 5 drops of cabbage juice in 3 compartments 2. Put 10 drops of drain cleaner in those same compartments 3. Count how many drops of aspirin solution it takes to neutralize (change

to purple) in compartment #1. _____ 4. Count how many drops of lemon juice it takes to neutralize compartment

#2. _____ 5. Count how many drops of vinegar it takes to neutralize compartment #3.

_____ 1 2 3

6. Which acid solution is most concentrated? __________ 7. Which acid solution is least concentrated? ______ 8. How do you know this? _____________________________________________ _____________________________________________ _____________________________________________ From Acid à Neutral 1. Put 5 drops of cabbage juice in 3 compartments 2. Put 10 drops of vinegar in those same compartments 3. Count how many drops of baking soda solution it takes to neutralize

compartment #1. _____ 4. Count how many drops of alka seltzer it takes to neutralize compartment

#2. _____ 5.    Count how many drops of drain cleaner it takes to neutralize compartment #3. _____  

 1. Which acid solution is most concentrated? __________ 2. Which acid solution is least concentrated? ______ 3. How do you know this? ____________________________________________ _____________________________________________ _____________________________________________

Household Mysteries Mrs G will do in class Acid, Base or Neutral?

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BrainPop: pH Scale

1. Which of these substances is acidic? a. Tap water b. Lemon wedge c. Floor cleaner d. Box of baking soda 2. What is the most likely pH of a tube of toothpaste? a. 3 b. 5 c. 7 d. 9 3. How is a standard hydrogen atom different from a hydrogen ion? a. A hydrogen ion has an extra electron b. A hydrogen ion is missing an electron c. A hydrogen ion has an extra proton d. A hydrogen ion is missing a proton 4. What might happen if you mixed a strong acid with an equally strong base? a. You would see an explosive chemical reaction b. The acid would destroy the base c. The base would destroy the acid d. You'd wind up with a pH-neutral substance 5. An extremely strong base would have a pH of: a. 1 b. 7 c. 9 d. 14 6. What might happen if buffers did not exist within the human body? a. Our blood and other bodily fluids might become too acidic or basic b. Our stomach acid would not be able to break down food c. We would not be able to process glucose within our cells d. We would not be able to inhale oxygen into our lungs 7. This piece of pH paper has been dipped into: [Blue pH paper] a. An acid b. A base c. A pH-neutral substance d. A buffer 8. Why do metals dissolve when you dip them in acid? [Dissolving metal] a. The buffers in the metal are eaten away by the acid b. The electrons in the metal are stripped away by hydrogen ions c. The hydrogen ions in the acid react with the hydroxyl ions in the metal d. The acid reacts with the basic metal to form carbon dioxide gas and salt 9. What might happen if acidic chemicals were emitted into the air by factories? Choose the best answer. a. The acid would destroy metallic elements in the air b. The acid would be neutralized by bases within clouds c. Acid rain might destroy ecosystems and farmland d. Violent chemical reactions would take place within the atmosphere 10. Healthy environments for life have a pH closest to: a. 1 b. 3 c. 7 d. 10

BrainPop: Acids and Bases 1. Which of the following substances is acidic? a. Baking soda b. Lemon-lime soft drink c. Distilled water d. Bar of soap 2. What happens immediately after you dissolve acid in water? a. Positively charged hydrogen atoms are released b. Hydronium ions are released c. Negatively charged hydrogen atoms are released d. Neutrally charged hydrogen atoms are released 3. Acids are caustic to the touch. In this context, what does "caustic" mean? a. Stinging or burning b. Pleasant c. Sarcastic d. Gentle 4. A hydronium ion is like a(n) ______ molecule with an extra hydrogen atom. a. Acid b. Base c. Water d. Vinegar 5. What substance would do the best job of cleaning pots and pans? a. A substance with a pH of 7 b. A substance with a pH of 2 c. A substance with a pH of 4 d. A substance with a pH of 8 6. What is a property of bases? a. Slippery touch b. Sour taste c. Ability to dissolve metal d. Ability to form hydronium ions 7. How do acidic solutions taste? a. Delicious b. Sweet c. Bitter d. Sour 8. Which of the following substances is basic? a. Apple juice b. Ginger ale c. Baking soda d. Distilled water 9. pH stands for: a. Potency of hydrogen b. Plurality of hydrogen c. Potential of hydrogen d. Pleurisy of hydrogen 10. What do acids and bases have in common? a. They both eat away at metal b. They can both conduct electricity c. They both have a sour taste d. They both form positively charged ions when dissolved in water

Acids: Record 5 Bullet Points in Little Book In everyday life we deal with many compounds that chemists classify as acids. For example, orange juice and grapefruit juice contain citric acid. These juices, and others, also contain ascorbic acid, a substance more commonly known as Vitamin C. Salads are often flavored with vinegar, which contains dilute acetic acid. Boric acid is a substance that is sometimes used to wash the eyes. In any chemistry laboratory, we find acids such as hydrochloric acid, sulfuric acid, and nitric acid. These acids are called mineral acids because they can be prepared from naturally occurring compounds called minerals. Mineral acids are generally stronger than household acids, and should be handled with great care because they can burn skin and clothing. Properties of Acids: Acids taste sour. Citric acid is responsible for the sour taste of lemons, limes, grapefruits, and oranges. Acetic acid is responsible for the sour taste of vinegar. Acids turn litmus indicator paper red.Litmus is a vegetable dye that may be either red or blue, depending on the acidity. When a sample of an acid is placed on red litmus paper, the color of the litmus does not change. Red litmus has been previously treated with acid. Adding more acid does not change the red color. However, when the same acid is placed on blue litmus paper, the color turns from blue to red. (Blue litmus has been treated with a base). Acids contain combined hydrogen. When a sample of zinc, a fairly reactive metal, is dropped into a test tube containing an acid such as hydrochloric acid, a reaction occurs.The bubbling in the tube indicates that a gas is released. When we test this gas by inserting a burning splint into the test tube,the gas burst into flame and produces a small popping sound. This is the characteristic test for hydrogen gas. In general, when certain acids react with metals, hydrogen gas is released. See following reactions: Zn (s) + 2HCl (aq) à H2 (g) + ZnCl2 (aq) Zn (s) + H2SO4 (aq) à H2 (g) + ZnSO4 (aq)

Acids are defined as substances that release hydrogen in water solutions. When an acid dissolves in water, the acid ionizes, releasing both hydrogen ions and ions of a nonmetal or nonmetallic polyatomic ion. Thus, when hydrochloric acid (HCl) is dissolved in water, the acid ionizes, forming hydrogen ions and chloride ions, as shown in the following equation: HCl (aq)à H+(aq) + Cl1- (aq) It is these H+ (aq) that are responsible for the properties of acids. Uses of Acids: Sulfuric acid is the chemical most widely used in industry. It is also used to make other acids such as hydrochloric & nitric acid and to remove the surface oxide layers on metals (pickling) before the metals are coated with materials that prevent rusting. For example, before iron is coated with chromium (in chromium plating), the iron is dipped into dilute sulfuric acid to remove the iron oxide normally present on the surface of the iron. Another important use of sulfuric acid is the storage cell. In a lead storage cell, dilute sulfuric acid serves as the electrolyte through which ions move between the lead plates, acting as the cathode, and the spongy lead dioxide, acting as the anode. Several such cells connected together make up the type of storage battery used in automobiles. Nitric acid, another important industrial acid, is used in the making of fertilizers, plastics, photographic film and dyes. It is also used in the preparation of such explosives as dynamite and TNT. Hydrochloric acid (HCl), like sulfuric acid, is used to clean metals clean brick and tile and in the manufacture of sugar and glue. It is produced in small quantities in the stomach where it aids digestion. Acid-Base Indicators: 4 Bullet Points! Many substances, which includes litmus paper, change color in response to acid or bases. The pigment in red cabbage juice is another natural substance very commonly used to show color change. Phenolphthalein is one of the most common indicators used for beginning chemistry, because its color change is very obvious which makes it easy to use. There are many other indicators that change colors at different pH’s. pH paper commonly contains a mixture of different indicators that change colors at different pH's. The mixture is applied to paper, and then compared to a color chart to see what the pH of a solution is, approximately. Remember indicators ARE NOT acids or bases.

Bases: Record 5 Bullet Points in Little Book Ammonium hydroxide, or ammonia water, is very irritating to the nose and the eyes. This substance, called a hydroxide, or a base, is often used in the home for cleaning because bases generally dissolve grease. Milk of magnesia (magnesium hydroxide), which is used as an antacid, is a base; lye (sodium hydroxide), which is used in the manufacture of soap, is another familiar example of base. Bases are ionic compounds containing metal ions and hydroxide ions. For example, sodium hydroxide contains sodium ions and hydroxide ions. When sodium metal is placed in water, sodium hydroxide is formed and hydrogen gas is released. Since the formula for water can be written as HOH instead of H2O, the reaction involves single replacement: 2 Na (s) + 2 HOH (l) à 2 NaOH (aq) + H2 (g) Properties of Bases: (in water solutions) 1. Bases taste bitter. A bitter taste is characteristic of all bases. It is the presence of a base that give unflavored milk of magnesia its bitter taste. 2. Bases feel slippery. If you rub a drop or two of household ammonia between your fingers, you experience the slippery feeling of a base. Wet soap is also slippery because of the presence of a base. 3. Bases turn red litmus blue. A common indicator, used to detect the presence of a base, is phenolphthalein which, when mixed with a base, turns pink. 4. Bases release hydroxide ions in water solutions. When dissolved in water, bases ionize releasing metal ions (or metallic polyatomic ions) and hydroxide ions. For example: when sodium hydroxide is dissolved in water, it ionizes as: NaOH (s) + H2O (l) à Na1+ (aq) + OH1- (aq) Bases are defined as substances that release hydroxide ions in solution. It is these OH1- (aq) ions that are responsible for the properties of bases. Uses of Bases: Ammonium hydroxide, frequently called ammonia, is used in the preparation of important related compounds such as nitric acid and ammonium chloride. Ammonia is also used as a cleaning agent.

Sodium hydroxide (NaOH) is used in the manufacture of soap, rayon, and paper. Strong solutions of this base are very caustic; that is, they are extremely harmful to the skin. Calcium hydroxide (CaOH), commonly known as slaked lime, is used in the preparation of plaster and mortar. Water solutions of calcium hydroxide, called limewater, can be used in the lab as a test for the presence of carbon dioxide. Neutrals: Record 5 Bullet Points in Little Book A neutral substance is a substance that shows no acid or base properties, has an equal number of hydrogen and hydroxyl ions and does not change the color of litmus-paper. Neutral Substances: Water is neither an acid nor a base, therefore it is neutral. Other are substances that neutral are classified as salts. Salts have a pH of 7. There are hundreds of different salts and they are named after the acid they are made from. See table below.

Name of Acid Name of Salts Examples hydrochloric acid chlorides sodium chloride, calcium chloride

nitric acid nitrates potassium nitrate, ammonium nitrate sulfuric acid sulfates copper sulfate, magnesium sulfate

carbonic acid carbonates calcium carbonate, sodium hydrogen carbonate Salts: 1) neutralization of acid and base--When an acid and base react, they counteract each other, that is, they neutralize each other. Such a reaction, known as a neutralization reaction, results in the formation of water and a salt.For example, when sodium hydroxide (NaOH) and hydrochloric acid (HCl) react, water and the salt sodium chloride are formed. NaOH + HCl --> NaCl + H2O. This occurs because the hydrochloric acid and the sodium hydroxide first ionize, and then react. The compounds ionize releasing hydrogen, chloride, sodium, and hydroxide ions. Since these are mobile in solution, hydrogen ions meet hydroxide ions and unite to form water. At the same time sodium ions and chloride ions remain as aqueous salt.

Summary: Properties of acids 1. They are liquids. 2. They are solutions of compounds in water. 3. If concentrated they can be corrosive. 4. Acids taste sour (for example, vinegar). 5. Turn blue litmus paper red - this is an easy test for an acid! 6. Usually react with metals to form salts. 7. Acids contain hydrogen ions. 8. Turns Universal Indicator from green to red, 9. Has a pH less than 7. Examples: vinegar (ethanoic acid) and lemon juice (citric acid) Some common acids used in chem labs at school are: 1. Hydrochloric acid, HCl(aq) 2. Nitric acid, HNO3(aq) 3. Sulfuric acid, H2SO4(aq) Properties of alkalis (bases) 1. They feel soapy to touch. 2. They are soluble bases. 3. Like acids, they can burn the skin. 4. They turn red litmus blue - this is how you test for an alkali! 5. Alkalis contain hydroxide ions (OH-). 6. They taste bitter. 7. Turns Universal Indicator from green to blue or purple. Some common bases (alkalis) used in chem labs at school are: 1. Sodium hydroxide, NaOH(aq) 2. Ammonia, NH3NH4OH(aq) (also known as: NH3 ) 3. Calcium hydroxide, Ca(OH)2(aq) Properties of neutral substances 1. Litmus paper is not affected by neutral paper. 2. Tend to be harmless 3. Universal Indicator stays green. Common examples of neutral substances: 1. Water 2. Sodium chloride solution, NaCl(aq)(common salt) 3. Sugar solution C6H12O6(aq)

The Strength of an Acid: Acids and alkalis can be strong or weak! So how can we measure their strength? The strength of an acid or alkali is shown using a scale of numbers called the pH scale. The numbers go from 0-14.

On the scale it follows that: An acidic solution has a pH number less than 7 An alkaline (basic) solution has a pH number greater than 7 A neutral solution has a pH number of exactly 7. You can find the pH of any solution using universal indicator. Universal indicator is a mixture of dyes. It comes as a solution or paper. Universal indicator will change from green to a different color depending on the pH of the solution you place it in.

Note: In a strong acid, nearly all the acid molecules form ions. In a weak acid, only some of the acid molecules form ions. The more OH- ions (hydroxide ions), the more alkaline (basic) an alkali will be, as in a STRONG base. This means, the more OH- ions the higher the pH number.