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pH, Acidic and Basic Solutions
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Acids Acids are substances that release positively charged hydrogen ions, H+, in the water. H+ will combine with water releasing a positively charged ion called hydronium (H3O)+ HYDRONIUM ions + charge - HYDROCHLORIC ACID HCl + H2O -----> (H3O)+ + Cl-
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Bases Bases are substances that release negatively charged hydroxide ions, OH-, in the water. NaOH +H2O > Na+ + OH- + H2O SODIUM HYDROXIDE H= and OH- is VERY IMPORTANT!!!!!!
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Strengths of Acids and Bases
The strength of an acid depends on how easily the acid will release H+ (hydrogen) ions when in water The strength of a base depends on how easily the base will release OH- (hydroxide) ions when in water
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Indicators Indicators are compounds that react with acidic and basic solutions and produce certain colors, depending on the solution’s pH. Indicators help you determine the pH of a solution.
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*Litmus paper is an indicator
It shows if a substance is an acid or a base: Red litmus paper in a base solution turns blue Blue litmus paper in an acid turns red
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3 *Universal Indicator Gives you more information than the Litmus paper because gives you the pH value of the substance
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pH and pH Scale pH is a measure of how acidic or basic a
solution is and depends on the concentration of hydronium and hydroxide ions. “pH stands for percentage hydrogen”
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pH and pH Scale The pH scale ranges from 0 to 14.
Acidic solutions have pH values below 7. A solution with a pH of 0 is very acidic. A solution with a pH of 7 is neutral. Basic solutions have pH values above 7.
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Mini Lab 1: Litmus paper In groups.
Each group has 2 substances ( vinegar and ammonia), 2 strips of red litmus paper and 2 strips of blue litmus paper. Dip one red strip and one blue inside each one of the substances and record your results on a table. VINEGAR, WATER, baking soda solution , milk of magnesia , ammonia
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Mini Lab 1: Litmus paper Ammonia Soda Red color ? Blue Acid or Base? ?
VINEGAR, WATER, baking soda solution , milk of magnesia , ammonia
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Mini Lab: Write a paragraph explaining why you obtained such results and if the substances you tested are acids or bases . Explain what is the role of the paper you used during the experiment and why did it changed color. VINEGAR, WATER, baking soda solution , milk of magnesia , ammonia
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Mini Lab 1: Litmus paper Ammonia Soda Red Turn blue Stay red Blue
Stay blue Turn red Acid or Base? base acid VINEGAR, WATER, baking soda solution , milk of magnesia , ammonia
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*Properties of Acidic Solutions
-sour taste -can conduct electricity because it has ions -are corrosive, which means they break down -certain substances. Many acids can corrode fabric, skin, and paper. -react strongly with certain metals.
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Uses of Acids Acetic Acid - vinegar and salad dressings
Citric Acid in limes, lemons and oranges Ascorbic acid – vit C Sulfuric acid - fertilizers, steel, paints, and plastics. Acids – batteries
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Properties of Basic Solutions
Slippery Bitter taste Bases are corrosive. can conduct electricity ( have ions) Basic solutions are not as reactive with metals as acidic solutions are.
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Uses of Bases soaps, ammonia, and many other cleaning products
Chalk is basic Blood is basic
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Neutralization *Neutralization is the chemical reaction of an acid with a base. Ex: NEW SUBSTANCES WILL FORM ACID AND BASE ARE NOT THERE ANYMORE, new substances will not release Hydrogen ion and hydroxide ion, new substances are neutral It is a chemical reaction because new substances are being formed ( salt and water)
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*How does neutralization occur?
Recall that every water molecule contains two hydrogen atoms and one oxygen atom. The reaction of a base and an acid results in water and a salt . Water has a neutral pH. It is called neutralization because the acid and the base are not there anymore……. HCl + NaOH NaCl + H20 ( neutral) BOOK MAKES IT TOO COMPLICATED ….. NOTES ARE WHAT YOU SHOUL KNOW
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Lab: Creating a pH scale
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