TAKS Review – IPC 9A

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TAKS Review – IPC 9A

Water as the universal solvent

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The universal solvent

Water is called the universal solvent.

This is because water can dissolve many things.

Structure of Water

Water looks like this:

O

H H

Partial NEGATIVE (-) charge

Partial POSITIVE (+) charge

Partial POSITIVE (+) charge

POLAR!

It has a positive end and a negative end. This is called polar (like a magnet). It dissolves other polar molecules. Water’s polarity helps it dissolve many

substances. (Do you see a pattern? We are using the

word “polar” a lot! This word shows up on TAKS frequently.)

O

H H

Ionic Bonds

Remember that ionic bonds are between metals and nonmetals.

The metal has a positive charge. The nonmetal has a negative charge. Because an ionic compound has a

positive and negative end, it is also considered a polar molecule.

NaClNaClKBrKBrmetal

metal

nonmetal nonmetal

Ionic Bonds

NaCl looks like this:

Partial POSITIVE (+) charge

Partial NEGATIVE (-) charge

Na Cl

Ionic Compounds in Water NaCl dissolved in water looks like this:

Notice how the NaCl separated and opposite charges are attracting.

NaNa

Na

Cl

Cl

Cl

-O

H+

H+ H

+

H+

O-

Water breaks the bonds between the Na

and Cl ions

Click here to view water dissolving an ionic compound

Nonpolar Molecules

Water dissolves other polar molecules.

It does NOT dissolve nonpolar molecules such as oil and fat.

Soluble in water? Show your answer by holding up the correct color card

Sugar _click for answer_ Cooking oil _click for answer_ Sand _ click for answer_ An ionic compound _ click for answer_ A nonpolar molecule _ click for answer_ Salt _ click for answer_ Wood _ click for answer_ A polar molecule __click for answer_

yes no

11

Soluble in water?

click here to go back to list

yes

12

Soluble in water?

click here to go back to list

11

no

Guided Practice

Water is often called the "universal solvent" because many common substances dissolve in water. Why do so many substances dissolve in water?

A. There is an abundance of water on Earth.

B. The water molecule only contains two elements.

C. The water molecule has a polar structure.

D. Hydrogen and oxygen are very reactive when they are combined.

click for answer

Guided Practice

Water is often called the "universal solvent" because many common substances dissolve in water. Why do so many substances dissolve in water?

A. There is an abundance of water on Earth.

B. The water molecule only contains two elements.

C. The water molecule has a polar structure.

D. Hydrogen and oxygen are very reactive when they are combined.

ANSWERANSWER

Guided Practice

Water is a polar molecule. This enables it to dissolve…

A. Rubbing alcohol

B. Mercury

C. Oil-based paints

D. Sandclick for answer

Guided Practice

Water is a polar molecule. This enables it to dissolve…

A. Rubbing alcohol

B. Mercury

C. Oil-based paints

D. Sand

ANSWERANSWER

Guided Practice

Which characteristic of a molecule most impacts whether it will dissolve in water?

A. Size

B. Polarity

C. Ionization energy

D. Shapeclick for answer

Guided Practice

Which characteristic of a molecule most impacts whether it will dissolve in water?

A. Size

B. Polarity

C. Ionization energy

D. Shape

ANSWERANSWER

Guided Practice

Follow the directions on your handout

“Show the Polarity of Water”

click here for answer

Guided Practice

Show the Polarity of Water

ANSWERANSWER

OH H

Cl

Na

v

TA K S R e v ie w - IP C TA K S R e v ie w - IP C

O b je c t iv e 5 BO b je c t iv e 5 B

W a v e W a v e

In t e r a c t io n s In t e r a c t io n s

Waves

2 Types of WavesTRANSVERSETRANSVERSE

– Particles in the medium move Particles in the medium move perpendicularperpendicular (up and down) (up and down) to the wave directionto the wave direction

– Hand motion is moving Hand motion is moving up and up and downdown

– Water wavesWater waves

LONGITUDINALLONGITUDINAL– Particles move Particles move parallel parallel (back and (back and

forth) to the wave directionforth) to the wave direction– Hand motion is moving Hand motion is moving back and back and

forthforth– CompressionCompression - part where - part where

molecules are molecules are pushed togetherpushed together..– RarefractionRarefraction- part where - part where

molecules are spread apartmolecules are spread apart– Sound wavesSound waves

Guided Practice This wave moves the medium in a direction

perpendicular (up and down) to the direction in which the wave is traveling.

longitudinal transverse

Click here for answer

Guided Practice ANSWER

transverse

Properties of a WaveTransverse Wave

Longitudinal (Compressional) Wave

Guided Practice The distance from crest to crest or trough to trough

on a transverse wave is _______________.

amplitude wavelengthclick here for answer

Guided Practice ANSWER

wavelength

Behavior of Waves Interference - the ability of two or more

waves to intersect and combine to form a new wave (composite wave).

Interference between waves can be constructive or destructive.

Constructive vs. Destructive Interference Waves

Troughs of one waveadd to troughs of another wave and crests add to crests, amplifying the new wave.

Troughs of one wave overlap crests of another wave, canceling each other out in the new wave.

Node- place where two waves cancel each other

C o n s t r u c t iv e

D e c o n s t r u c t iv e

Guided Practice Does this show constructive or deconstructive

interference?

destructive constructive

Click here for answer

Guided Practice ANSWER

The two waves are in phase in that the crests and troughs of one wave add to the crests and troughs of the

second wave.

constructive

Wave Demonstration #1

Longitudinal vs. Transverse Waves

O c c u r s w h e n a w a v e s t r ik e s a s u r f a c e a n d b o u n c e s o f f o f t h e s u r f a c e

All types of waves can be reflected.

The a n g le o f in c id e n c e of a wave i s a lw a y s e q u a l t o the a n g le o f r e f le c t io n .

N o r m a l - an imaginary line perpendicular to a reflective surface.

Reflection

R e f le c t e d R a yIn c id e n t R a y

Refraction

The greater the change in speed is, the more the wave bends.

the bending of a wave caused by a change in its speed as it moves from one medium to another.

Air

Resonance

Air

The ability of an object to vibrate when it absorbs energy at its natural frequency.

Natural Frequency - a special frequency at which objects vibrate if they are disturbed. All things in the universe have a natural frequency.

When one tuning fork is struck with a mallet, it begins to vibrate sending out energy that is absorbed by the second one causing it to vibrate at its natural frequency.

Wave Demonstration #2

Resonance & Natural Frequency

Diffraction

Example, you can hear someone talking around the corner because the waves move beyond the wall.

When waves spread out past a barrier.

BarrierWaves approaching Barrier

Waves enter Barrier and spread out in this manner

Polarization the process of transforming unpolarized light into polarized light

Polarized sunglasses reduce blinding glare from water, car hoods, and highways by filtering out horizontal light waves (last filter is vertical).

Since last filter is horizontal, the vertical waves are being filtered out.

Filters have tiny slits

Wave Demonstration #3Polarization

Wave Card SortStudents work in pairs to match wave diagrams. One baggie per pair.

Click here for answers to card sort

Wave Card Sort Answers1. Wavelength2. Amplitude3. Refraction4. Nodes and Antinodes5. Incident Ray6. Reflected Ray7. Crest of Wave8. Trough of Wave9. Destructive Interference10. Compression11. Rarefaction

Mini-TAKS Assessment

Students take assessment

Review Mini-TAKS Answers

Click here for assessment answers

Mini-TAKS Answers1. B2. B3. C4. B

5. C6. A7. A8. B

9. D10. D11. B12. B13. A