Science 7 Notes 21

Acids 1. Differentiate

Bases between an and ion 2. Describe the relationship pH between ,

bases, and pH

Describe why + has a Water molecules occasionally split apart and form a hydrogen ion (H ) and a netural pH. hydroxide ion (OH-) as shown below:

+ - H2O H + OH - OH  In pure water, 1 out of 550 million water molecules will split in this

way  Because the number H+ ions equal the number of OH- ions, pure water has a neutral pH

Describe the charateristice of Acids an acid.

• Compounds that dissolve in water and will split into hydrogen ions (H+) and negative ions + - • HCl → H + Cl • They contain excess hydrogen ions (H+)

• sour • Turns paper red • Examples: HCl, HNO , H SO 3 2 4

Describe the Bases charateristics of a base. • Compounds that dissolve in water and will split into positive ions (H+) and hydroxide ions (OH-) • In Water… NaOH → Na+ + OH- • Form excess hydroxide ions (OH-) • bitter • Turn litmus paper blue • Examples: NaOH, KOH, Mg(OH)2, Ca(OH)2

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Science 7 Notes 21

pH (Potential of Hydrogen) What does the pH scale measure? + • A measurement scale to indicate the amount of H ions compared to Describe the - range of the pH OH ions in a solution scale. • The pH scale ranges from 0 to 14 – At a neutral pH (pH 7), + the concentration of H ions - equals the concentration of OH ions – At an acidic pH (pH less + than 7), there are more H ions - than OH ions

- – At basic pH (pH greater than 7), there are more OH ions than What is the pH of + a neutral H ions substance?

What is the pH of an acidic Neutralization substance? • If you react an acid with a base they will neutralize each other What happens when you mix an • Neutralization reactions produce a compound + water acid with a base? • HCl + NaOH → ______+ ______

Put the following substances in order of increasing acidity: coffee, bleach, orange juice,

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