1. Acids and Bases

2. Acid and Base Notes

3. I can distinguish between an acid and a base.
I can list the characteristics of an acid and a base.
I can name acids.
I can name bases.

4. What do you think an acid is?
Give an example of an acid.

5. An acid is a compound that forms H+ ions when dissolved in water.
Examples of acids include HCl, H2SO4 and HBr.
Common household acids: vinegar, lemon juice, and coffee.

6. Acidic compounds taste sour, like citrus fruits, vinegar, and yogurt.
Acids cause cuts on your hands to burn.

7. Acids react vigorously with many metals, including zinc, magnesium, and iron.
Acids form electrolytes (ions) when dissolved in water.
Electrolytes make it possible for solutions to conduct electricity.

8. Acids cause indicators to change color, like litmus paper.
An acid base indicator turns one color in an acid and a different color in a base.
Acids react with bases to form water and a salt through neutralization reactions.

9. What is a base?
Give an example of a base.

10. A base is a compound that forms OH- ions when dissolved in water.
Examples of bases include: NaOH, LiOH and Ca(OH)2
Bases taste bitter and feel slippery.
Many cleaning agents are bases.

11. Bases do not react with most metals.
Bases also cause indicators to change colors.
Bases also form electrolytes (ions) when dissolved in water to conduct electricity.
Both acids and bases can form weak or strong electrolytes.

12. Naming Acids
All acid formulas start with hydrogen, followed by an anion (negative ion).
The exception to this rule is water, which can be an acid or a base.
To name an acid, you need to look at the anion (the second part).

13. If the anion is a single element from the periodic table, the acid name begins with the prefix hydro-.
The name of the element follows hydro-.
The element name then ends with –ic.

14. All acids end with the word acid.

15. Examples:
HCl HF

16. If the anion is a polyatomic ion, there are two different endings.
A) For anions ending with –ite, you change the ending to –ous.
B) For anions ending with –ate, you change the ending to –ic.
C) Remember to add acid to the end of all acid names.

17. Examples:
Polyatomic ion SO3-2 ___________
Acid: H2SO3 ______________________
Polyatomic ion: NO3- __________________
Acid: HNO3 __________________________

18. Naming Bases All bases end with the polyatomic ion OH-.
To name a base, you write the name of the first element straight off the periodic table.
All bases then end with hydroxide.

19. Example:
NaOH _________________________
Ca(OH)2 ________________________

20. Review Questions What is an acid? What are the properties of an acid?
What is an indicator?
What is a base?
What are the properties of a base?

21. pH Scale

22. I can define an acidic and basic solutions.
I can explain the pH scale and identify where acids, bases, and neutral are.
I can calculate the pH and the pOH.
I can explain why buffers are important.

23. Which ion do you think would be higher in concentration in an acid, H+ or OH-?
Which ion do you think would be higher in concentration in a base, H+ or OH-?

24. An acidic solution is one where the hydrogen ion concentration is higher than the concentration of the hydroxide ion.
A basic solution is one where the hydroxide ion concentration is higher than the concentration of the hydrogen ion.

25. Basic solutions are also called alkaline solutions.
The pH scale is a measure of the hydrogen ion concentration (aka acidity).

26. What is the range of the pH scale?
Where do you think neutral is on the pH scale?

27. The pH scale ranges from 0-14.
A) Acids have a pH less than 7.
B) Neutral solutions have a pH equal to 7.
C) Bases have a pH greater than 7.

28. Acids and bases can be strong or weak.
The strength of an acid or base depends on how easily they break apart in water to form ions or electrolytes.

29. Where will strong acids be on the pH scale, closer to 0 or closer to 7?
Where will strong bases be on the pH scale, closer to 7 or closer to 14?

30. The closer the pH is to 0, the stronger the acid.
The closer the pH is to 14, the stronger the base.

31. The concentration of the hydroxide ion can also be measured using pOH.
Remember, acids form H+ ions and bases form OH- ions in water.
There is a relationship between pH and pOH.

32. Formulas:
pH + pOH = 14
pH= 14 - pOH
pOH= 14 - pH

33. The pH scale was developed based on logarithms.
The p stands for -log of and the H stands for hydrogen.
Given the concentration of hydrogen, the pH can be calculated using the following equation:
pH = -log[H+]

34. Going from a pH of 3 to a pH of 2 is a 10 fold increase in the concentration of H+ because of the logarithmic scale.

35. Example: Calculate the pH of a solution if the hydrogen ion concentration is 8.7 x 10-4.

36. The pOH can be calculated the same way as the pH, if you know the concentration of hydroxide ions.
pOH = -log[OH-]

37. Calculate the pOH of a solution that has a OH- concentration of 5
Calculate the pOH of a solution that has a OH- concentration of 5.0 x 10-2

38. A buffer is a mixture that is able to release or absorb H+ ions, keeping a solution’s pH constant.
Buffers play an important role in organisms because drastic changes in pH can kill cells.

39. Review Questions What is the pH scale?
Where are acids and bases on the pH scale?
Where are strong acids found on the pH scale?
Where are strong bases found on the pH scale?
Where is neutral on the pH scale?
What is the relationship between pH and pOH?

40. Acid Base Reactions

41. I can write the general acid and base reaction.
I can predict the products of an acid base reaction.
I can give an example of a neutralization reaction.
I can explain how acid rain is formed.
I can describe the consequences of acid rain.
I can explain why limestone helps neutralize acid rain.

42. When an acid and base react, what are the products?

43. In general, the reaction of an acid with a base produces water and a salt.
A salt is a metal bonded to a non-metal.
Salt consists of an anion (-) from the acid and a cation (+) from the base.

44. Water is formed from the H+ from the acid and the OH- from the base.
Neutralization reactions occur when an acid reacts with a base to produce water and a salt.
Neutralization reactions are double replacement reactions.

45. The reactants switch partners to form the products.
HA + BOH  _____ + _____
Acid + Base  Salt + Water

46. HCl + NaOH  _____ + _____

47. Why do people take antacids?

48. Antacids work based on acid-base neutralization reactions.
The acid in your stomach reacts with the antacid to produce salt and water.
Acid base neutralization reactions also help explain why limestone helps control pH in lakes.

49. What is acid rain?
What causes acid rain?
What are the consequences of acid rain?

50. Normal rain water has a pH near 6.
Rainwater with a pH less than 5.6 is defined as acid rain.
Acid rain is caused mainly by burning coal.
Even though coal is mostly carbon, it does contain small amounts of sulfur.

51. When burned, the sulfur in coal reacts with oxygen to form sulfur dioxide and sulfur trioxide.
These compounds then react with water in the atmosphere to form acids.
SO2 (g) + H2O (l)  H2SO3 (aq)
SO3 (g) + H2O (l)  H2SO4 (aq)

52. Acid rain can also form when nitrogen in the atmosphere reacts with oxygen.
At high temperatures, nitrogen will react with oxygen to form NO2.
Nitrogen dioxide then reacts with water to form nitric acid and nitrous acid.
2NO2 + H2O  HNO3 + HNO2

53. Any combustion reaction, including automobile engines, that produces high temperatures can trigger the formation of NO2.
Acid rain damages metals and many stone building materials.
Acid rain also washes nutrients out of the soil, damages bark and leaves.

54. Acid rain eventually is added to lakes, rivers, and streams.
If the pH of a river or lake falls below 4.5, most aquatic species cannot survive.

55. Limestone acts like a base, even though it is calcium carbonate. CaCO3
Acid rain changes pH in lakes and groundwater.
When acid rain and limestone react, the products are salt, water and CO2.

56. Therefore, limestone lakes can neutralize acid rain.
Lakes with granite bottoms cannot neutralize acid rain.

57. CaCO3 + H2SO4  CaSO4 + H2O + CO2 Limestone acid rain salt
Equation for acid rain and limestone:
CaCO3 + H2SO4  CaSO4 + H2O + CO2
Limestone acid rain salt

58. What is a neutralization reaction?
What are the products of an acid base reaction?
What is a salt?
What causes acid rain?
What can neutralize acid rain in lakes?