Do Now for 3/21/13

Open Books to page C-92.

HW: Complete procedure for part B

C48 Mixing an Acid and a Base

• Today’s Target: I will be able to see what happens when we mix an acid and a base together.

• Introduce Lab.• Lab safety• Gather data• Discuss Data• Discuss and design a procedure for part B• Return work

C48 Mixing an Acid and a Base

• What do we Know?– Acid characteristics:– Base characteristics:– _______ can tell us whether a substance is

an acid, base, or neutral substance. They can also tell us the approximate concentration of an acid or base.

– The more dilute an acid or base is, the more it behaves like ________.

C48 Mixing an Acid and a Base

• One possible way we can neutralize acids and bases is to add ____________.

C48 Mixing an Acid and a Base

• What if we mix an acid and a base together? What happens to the pH of the mixture?

C48 Mixing an Acid and a Base

• Goggles and aprons.• Wash and dry your tray first.• Wash and dry all equipment when done.• Wash hands.• Remember, we are making QUALITATIVE

OBSERVATIONS (colors)

C48 Mixing an Acid and a BaseDrops of Potassium Hydroxide (KOH) added to 10 drops of Hydrochloric acid (HCl)

Universal Indicator Color

0

1

2

3

4

5

6

7

8

9

10

C48 Mixing an Acid and a Base• For part B, you need to design a

procedure that determines how many drops of Base it will take to neutralize our acid, and how many drops of acid it will take to neutralize our base.

• How will you know when either solution is neutral?

• You will need a data table, what heading will you have?

Do Now for 3/22/13

• Take out your procedure for Part B• HW: Answer analysis questions 1

through 4 on page C-93• Quiz on C47 and 48 on Monday

C48 Mixing an Acid and a Base

• Lab Safety and Procedure.• Gather Data.• Graph Data• Analysis.

C48 Mixing an Acid and a Base

• Goggles and aprons.• Wash and dry your tray first.• Wash and dry all equipment when done.• Wash hands.• How will we know when our solutions are

neutral???

C48 Mixing an Acid and a Base

• CUP 1 CUP 5

Drops of BASE added to 10 drops of ACID

Universal Indicator color

EstpH

Drops of ACID added to 10 drops of BASE

Universal Indicator color

EstpH

C48 Mixing an Acid and a Base

• Lab Tips– Make sure your are using the correct liquid– Do not mix the caps– Think about the pH scale, if you go past

neutral to the acid side, will you get back to neutral by adding more ACID?

• When you are done gathering data, add your results to the table on the screen.

• 1. What happens as you add an acid to a basic solution or add a base to an acidic solution?– It first becomes closer to neutral. Eventually

when you add too much, you overshoot the neutral point.

• 2. Which solution seems more powerful in this investigation, the acidic or the basic? Explain your answer.– The acid seems more powerful because it

takes a greater number of drops of base than acid to produce a neutral solution.

• 3. Based on what you know so far, which do you think is a better way of neutralizing an acid: diluting it with water, or adding a base? Explain your answer.– Some students will think dilution is better

because you only need water. Others might be concerned that when you add the base you are creating another product. And some will think neutralization is better, because dilution requires a huge volume of water.

• 4. Given two solutions, how might you determine: a. whether these solutions are acidic or basic?– Test them with universal indicator solution or

pH paper. If it turns blue, it is a base, and if red, it is an acid.

• b. which is more acidic or basic?– Mix equal amounts together and test with

universal indicator. Whichever one is more powerful will show up with the indicator. If it turns blue, the base is more powerful. If it turns red, the acid is more powerful.