Chemistry. Friday, April 27 th Monday, April 30 th, 2018

Transcription

1 Chemistry Friday, April 27 th Monday, April 30 th, 2018

2 Do-Now: BrainPOP: Acids & Bases 1. Write down today s FLT 2. The ph scale ranges from to. 3. Which is more acidic: ph 3 or ph 6? 4. Which is more basic: ph 3 or ph 6? 5. If you have a ph of 3, what is your poh? 6. What is the ph of a solution if the [H + ] is 1.5 x 10-6 M? Show all steps. 7. Take out your planner and ToC

3 FLT I will be able to define strong acids and weak acids & define the products of an acid-base reaction by completing Ch. 16 CN part C Standard HS-PS3-1: Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known

4 Ch. 16: Acid/Base Strength & Neutralization

5 Recall

6 Recall The ph scale ranges from 0-14 What s more acidic? What s more basic?

7 Brønsted-Lowry acids: Donate H + in water Recall Brønsted-Lowry bases: Accept H + in water

8 Acids and bases are electrolytes This means that they dissociate into ions in water Recall

9 Recall What if they only dissociate a little bit?

10 Electrolytes and Nonelectrolytes Weak electrolytes = only partially ionize Weak electrolytes have only a fraction of the solute that exists as ions (about 1%) Weak acids and bases; ammonia, acetic acid

11 Acid/Base Strength

12 Acid/Base Strength Acids are classified as strong or weak depending on the degree to which they ionize in water

13 Acid/Base Strength Strong acids = completely ionize in water Ex/ HCl, HNO 3, H 2 SO 4 HCl (g) + H2O (l) à H3O + (aq) + Cl- (aq) 100% ionized

14 Acid/Base Strength Weak Acids = ionize only slightly in water. Ex/ Ethanoic (acetic) acid CH 3 COOH (aq) + H 2 O (l) ßà H 3 O + (aq) + CH 3 COO- (aq)

15

16 Acid/Base Strength Bases are also classified as strong or weak depending on the degree to which they ionize in water

17 Acid/Base Strength Strong bases = completely dissociate into metal ions and OH - ions in water Ex/ Ca(OH) 2, NaOH, KOH

18 Acid/Base Strength Weak Bases = Produce a small amount of OH - in water Ex/ Ammonia (NH 3 ) NH 3(aq) + H 2 O (l) ßà NH 4 + (aq) + OH - (aq) 99% NH 3 still present, ~1% ionized

19 Conjugate Acids & Bases

20 The Brønsted-Lowry Definition We can label our acid-base reactions using proton-transfer Ex 1: Donated (Lost) H + HCl (aq) + H 2 O (l) à H 3 O + (aq) + Cl- (aq) Acid Base Accepted (gained) H + Ex 2: Accepted (gained) H + Acid NH 3(aq) + H 2 O (l) ßà NH 4 + (aq) + OH - (aq) Base Donated (Lost) H +

21 Conjugate Acids & Bases In this equation, what is the acid? What is the base?

22 Conjugate Acids & Bases Note: This is a reversible reaction. The back reaction is also an acid-base reaction. Which is the acid and which is the base?

23 Conjugate Acids & Bases Conjugate Acid = formed when a base gains H +

24 Conjugate Acids & Bases Conjugate Base = formed when an acid loses H +

25 The Brønsted-Lowry Definition We can label our acid-base reactions using proton-transfer Ex 1: Donated (Lost) H + Ex 2: HCl (aq) + H 2 O (l) à H 3 O + (aq) + Cl- (aq) Accepted (gained) H + Accepted (gained) H + NH 3(aq) + H 2 O (l) ßà NH 4 + (aq) + OH - (aq) Base Acid Acid Base Conj. acid Conj. acid Donated (Lost) H + Conj. base Conj. base

26 Try This: In the equation below, label the acid, base, conjugate acid, and conjugate base. Donated (Lost) H + HNO 3(aq) + CH 3 OH ßà CH 3 OH 2 + (aq) + NO 3 - (aq) Acid Base Accepted (gained) H + Conj. acid Conj. base

27 Conjugate Acids & Bases Conjugate Acid-Base Pair Strengths: Strong acids/bases form weaker conjugates Weak acids/bases form stronger conjugates

28 Last Tidbits

29 Last Tidbits Amphoteric substances = act as both an acid or a base NH 3 + H 2 O NH OH 1- base acid c.a. c.b. HCl + H 2 O H 3 O 1+ + Cl 1- acid base c.a. c.b.

30 Last Tidbits Neutralization Reaction - a reaction in which an acid and a base react in an aqueous solution to produce a salt and water: HCl (aq) + NaOH (aq) à NaCl (aq) + H 2 O (l) H 2 SO 4(aq) + 2KOH (aq) à K 2 SO 4(aq) + 2 H 2 O (l) Table 19.9, page 613 lists some salts

31 Last Tidbits Acid + Base à Water + Salt Properties related to every day: antacids depend on neutralization farmers adjust the soil ph formation of cave stalactites human body kidney stones from insoluble salts

32 Pair-Share-Respond 1. Distinguish between strong and weak acids 2. Distinguish between strong and weak bases 3. What are conjugate acids? 4. What are conjugate bases? 5. How can you determine if your conjugate acid/base is strong or weak?

33 Chemistry Tuesday, May 1 st Wednesday, May 2 nd, 2018

34 Do-Now: Ocean Acidification Notes 1. Write down today s FLT 2. Distinguish between a strong acid and a weak acid 3. Provide an example of a strong base 4. Provide an example of a weak base 5. What will be the conjugate acid of the base you wrote in #4? 6. Will the conjugate base of CH 3 COOH (acetic acid) be strong or weak? How do you know? 7. Take out your planner and ToC

35 FLT I will be able to describe the process of ocean acidification and its effects by completing Ocean Acidification Notes Standard HS-PS3-1: Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known

36 Ocean Acidification

37 Recall

38 The ph scale Recall This scale is logarithmic. Each ph represents how much of a change in acidity?

39 Ocean Acidification The ocean naturally absorbs carbon dioxide (CO 2 ) from the atmosphere

40 Ocean Acidification One environmental change that has significant effects is ocean acidification Human activities release CO 2 into the atmosphere While the ocean is a carbon sink, the deep ocean can only store so much CO 2 What happens when more CO 2 is being absorbed than the ocean can naturally regulate?

41 Ocean Acidification

42 Ocean Acidification Does this affect our marine organisms?

43 Video Questions 1. What % of CO 2 produced by human activity is dissolved in the ocean? 2. From s, what happened to the ph of the ocean? 3. What acid is formed when CO 2 reacts with H 2 O? 4. What does this acid release into the ocean? 5. What is happening to CaCO 3, and how is that affecting organisms in the ocean? 6. Add two additional video notes from the remainder of the video.

44 Demonstration Next, we will look at a demonstration to try to see if we can get a sense of what is happening Remind your group: what is an indicator? Why is it useful?

45 Demonstration Follow all directions read carefully! Record all data Keep track of the color visually Use gloves!

46 Demonstration Follow all directions read carefully! Use the color chart below to track your ph Note where you see the color change first Use a graduated cylinder for your vinegar

47 Chemistry Thursday, May 3 rd Friday, May 4 th, 2018

48 Do-Now: Ch. 16 Quiz Day Do-Now 1. Write down today s FLT 2. What is the formula for ph? 3. How do you determine how many decimal places your ph should have? 4. Distinguish between the acids hydrophosphoric acid and phosphoric acid 5. Copy the equation: H 2 CO 3 + H 2 O à H 3 O + + HCO 3-6. Identify the base and conjugate base in the reaction in #5