C ONDENSED S TATES Chemistry Spring 2015. A GENDA 3/2/15 Hard Boiled Egg?? Tests Back? Learning...

CONDENSED STATESChemistry Spring 2015

AGENDA 3/2/15

Hard Boiled Egg??

Tests Back?

Learning Targets for Unit 3 Review from 1st Semester

Notes over the review Topics

HW: Complete the Phase Change Graphic **Tomorrow TESTING DAY**

04/21/23copyright www.brainybetty.com 2006 All Rights Reserved 3

ENERGY AND PHASES REVIEW

1. Potential vs Kinetic Ea. PE = stored energy

Breaking bonds increases PE Making bonds releases PEb. KE = E of motion KEgas > KEliquid > KEsolid



2. Exothermic vs Endothermica. Exothermic Gives off E (E is released to surroundings) Bond formation Gas liquid solid (“intermolecular force

formation”) Why? I am forming bond, making things more stable –

energy is released.



b. Endothermic Absorbs E (E taken from surroundings) Bonds breaking Solid liquid gas (“intermolecular force

breaking”) Why? Energy is needed to break bonds.

**BARF**Break, absorb, release, form



Solid

Liquid Gascondensation

evaporation

freezing

meltingsublimation

deposition



Inside Arrows: Exothermic (feels hot) Decreases PE Forming IM forces More order Particles closer



Outside Arrows Endothermic (feels cold) Increases PE Breaking IM forces Less order Particles spread out



3. Heat vs Temperaturea. Heat Form of energy Measured in Joules (J) kJ (1000 J) Flows from warmer object to colder object



b. Temperature Measure of average KE of particles How much particles are moving E given to particles increase motion

increase T Measuring Temperature

Celsius vs Kelvin2 different temperature scales

K is a more direct reflection of KE

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Celsius (oC) Kelvin (K)

Absolute zero -273oC 0 K

Freezing point of water

0oC 273 K

Boiling point of water

100oC 373 K

Remember: K = C + 273

AGENDA 3/4/15

Hand Back Unit 2 Tests 5 Minute Remediation

Notes on Solutions and Solubility Solubility Curves

Pre-Lab for Solubility Lab Tomorrow

HW: Complete Solubility Curve WS

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SOLUTIONS

SolutionsHomogeneous mixture is the

same throughoutStable won’t spontaneously

separateExamples: Kool-Aid, saltwater,

popMade of 2 parts:

Solute – chemical that is dissolved (Kool-Aid mix)

Solvent – chemical that does the dissolving (water)

04/21/23Free template from www.brainybetty.com 14

SOLUTIONS

Aqueous Solution – a solution where H2O is the solvent

Why do things dissolve?Molecule – Ion AttractionSimilar chemical structure


SOLUTIONS

+ - +

+- -

-

+

++ - -

NaCl (s)

OH

H

O

HH

+H

H

H

H

H

H

O

O

O

OH

H

Na+ (aq)


SOLUTIONS

+ - +

+- -

-

+

+- -

NaCl (s)

O

H

H

O

H

HH H

H

H

H HO

O

O

OH

H

Na+ (aq)

-

Cl- (aq)+


SOLUTIONS

SolvationOccurs on the surface of a

solidMay be exothermic or

endothermicHeat of Solution – energy

change caused by dissolvingEx: acid in water is warm

AGENDA 3/5/15

Finish notes on Solutions and Solubility

Solubility Lab of Ammonium Chloride Solubility Curves

Examples of Solubility Curves

Notes on Molarity Practice Problems

HW: Complete Solubility Lab

WARM-UP

What is a solute?

What is a solvent?

What are three ways to dissolve solids faster?

Explain solvation to your partner.

How do you get things to dissolve faster?


SOLUTIONS

Factors that affect the rate of solvation:1. Stirring – fresh solvent is brought to surface of solute (faster)

2. Increase T – solvent molecules have more KE (faster)

3. Surface area – powder dissolves faster than a chunk


SOLUTIONS

*LIKES DISSOLVE LIKES*

water & food coloring“miscible”2 substances are alike and will mix

water & oil“immiscible”2 substances are different and will not mix

SOLUBILITY LAB

Safety: Do not reach over the hot plate

Tips: Heat the test tube in the water very gently Use the distilled water in the test tube only Use tap water in the beaker Make sure you know the amount of Ammonium

Chloride your group is responsible for.

AGENDA 3/6/15 Wrap-Up Solubility Lab

What does it mean?

Notes on Solubility Curves Saturation/Super-Saturation

Practice Problems with Solubility

Notes on Molarity Practice Problems

HW: Complete Solubility WS

SOLUBILITY LAB

What was the solubility of Ammonium chloride at 55 degrees C?

What would the solubility be at 85 degrees C?

What would the solubility be at 35 degrees C?

What does our best-fit line tell us about the solubility of Ammonium chloride?

Solubility – the maximum amount of solute that can be dissolved in a given amount of solvent

SOLUBILITY CURVES

Solid in Liquid Solutions - 3 “stages”1.Unsaturated

• Contains less than the maximum amount of solute

• All solute dissolves and there is room for more

SOLUBILITY CURVES

2. Saturated maximum amount of solute is dissolved additional solute will not dissolve at that T depends on T occurs when rate of dissolving = rate of

crystallization

SOLUBILITY

3. Supersaturated more solute dissolved than the solution

would normally hold can make by carefully cooling a saturated

solution unstable, wants to crystallize

SOLUBILITY

= dissolving = crystallizing

Sugar cubedissolving in

H2O

Some dissolvesSome crystallizes

Equilibriumdissolving = crystallization

Solution is saturated!

AGENDA 3/9/15

Review Solubility Check HW

Notes on Molarity

Practice Problems with Molarity

HW: Complete Molarity WS

SOLUTIONS WARM-UP

Explain the following terms:

Unsaturated

Saturated

Supersaturated

How do we measure the amount of solute in a solvent?

Concentration – the amount of solute dissolved in a given amount of solvent

Dilute – small amount of solute (weak)Concentrated – a lot of solute (strong)

MOLARITY

Molarity A unit of concentration # of moles of solute per 1 L of solution

Molarity (M) = moles of solute = mol Liters of solution L

MOLARITY

Examples:

A salt solution has a volume of 152 mL and contains 0.90 mol NaCl. What is the molarity of the solution?

MOLARITY

M = molL

152 mL = 0.152 L

M = 0.90 mol 0.152 L

= 5.9 M

MOLARITY

A 3.0 L aqueous solution contains 45.0 g KI. What is the solution’s molarity?

45.0 g KI166.00 g KI

1 mol KI=0.271 mol KI

M = molL

M = 0.271 mol3.0 L

M = 0.090 M

MOLARITY

How many moles of NaCl are in 1.5 L of a 3.0 M NaCl solution? What mass of salt is this?

M = molL

3.0 M = x mol 1.5 L

x = 4.5 mol

3.0 M(1.5 L) = x mol

MOLARITY

4.5 mol NaCl58.44 g NaCl

1 mol NaCl=262.98 g NaCl

260 g NaCl

AGENDA 3/10/15

Check Molarity HW Warm-Up

Notes on Dilution

Salt Lab

HW: Write-Up Lab

WARM-UP

Example: A 500.00 mL solution of HCl contains 45.0 grams of the chemical. What is the molarity of this solution?

Ans: 2.47 M

ANSWERS TO 1-5 ON SOLUTIONS PRACTICE

1. .901M2. 83.9 g KCl3. 6.09M4. 1.47 x 106 g KOH5. 20.5 M Pb in Sn

DILUTIONS

Dilutions – making a less concentrated solution from a stock solution

soln of known concentration

DILUTIONS

M=mol/L → M x L = mol

M1V1 = moles of solute before dilution

M2V2 = moles of solute after dilution

The moles of solute does not change during a dilution. You’re just adding more water.

DILUTIONS

M1V1 = M2V2

DILUTIONS

Examples:

How would you prepare 305 mL of 0.500 M AgCl from a 1.20 M stock solution?

DILUTIONS

M1 = 1.20 M

V1 = ?

M2 = 0.500 M

V2 = 305 mL = 0.305 L

M1V1 = M2V2

DILUTIONS

(1.20M)(V1) = (0.500M)(0.305L)

(1.20M)(V1) = 0.1525

1.20 1.20

V1 = 0.127 L

V1 = 127 mL127 mL of stock soln& 178 mL of H2O

DILUTIONS

To prepare 1.00 L of 6.0 M HCl, what volume of concentrated (12.1 M) HCl must be used?

M1 = 12.1 M

V1 = ?

M2 = 6.0 M

V2 = 1.00 L

M1V1 = M2V2

DILUTIONS

(12.1 M)(V1) = (6.0 M)(1.00 L)

(12.1 M)(V1) = 6.0

12.1 12.1

V1 = 0.496 L

V1 = 0.50 L500 mL of 12.1 M HClshould be addedto 500 mL of H2OV1 = 500 mL

SALT SOLUTIONS LAB

Safety: Bunsen Burners: Keep your hair tied back

Tips: Have the fresh samples of water ready to go

while boiling the first solution and salt solutions.

Keep data on the back of the lab for easy reference.

Be sure to use distilled water, not tap water.

AGENDA 3/11/15

1st Hour: Complete Lab, graph and conclusion

7th and 8th: Review Findings in the lab

Practice Dilution and Molarity calculations

HW: Finish any make-up work you have left

SALT LAB WARM-UP

Answer these questions with your partner:

1. How did adding the salt to the water affect the boiling temperature of the water?

2. How did diluting the salt concentration affect the boiling temperature of the water?

3. Bonus question: Why would adding salt to pasta water make the pasta cook faster?

CONCLUSION

Take time to write up your lab conclusion.

When you are complete turn in your lab and pick up the dilutions worksheet.

When finished with the dilutions worksheet, pick up the molarity and dilution worksheet.

AGENDA 3/12/15

1st Hour: Collect Lab

Check Dilutions Hw

Notes on Evaporation and Boiling Boiling Demonstration

Colligative Properties

HW: Complete WS as study guide for Quiz

SALT LAB WARM-UP

Answer these questions with your partner:

1. How did adding the salt to the water affect the boiling temperature of the water?

2. How did diluting the salt concentration affect the boiling temperature of the water?

3. Bonus question: Why would adding salt to pasta water make the pasta cook faster?

PHASE CHANGE: EVAPORATION

Evaporation – Process of changing from l

g Occurs at any T Occurs at the surface of the

liquid


Saturated air with vapor (“air is full”)


Vapor PressureThe pressure (collisions) caused by the vapor

above a liquid in a sealed container of equilibrium

Caused by the collision of vapormolecules with the surface of theliquid


VP depends on: T (as T ↑, evaporation ↑, vapor ↑ and VP ↑)

Because more molecules have the E to break free of the surface

T (as T ↓, evaporation ↓, vapor ↓ and VP ↓) Because fewer molecules have E to break free of

the surface

PHASE CHANGES: BOILING Occurs when the VP of a liquid = the atm P

on it Vapor forming within the liquid, not at surface The pressure from the atmosphere would crush

bubbles

P inside = P outside

PHASE CHANGE: BOILING

Boiling Point – T at which VP = atmospheric P Normal Boiling Point (NBP) = BP when P = 1 atm

P inside = P outside

PHASE CHANGE: BOILING

Why would the vapor pressure need to be equal to or greater than the atmospheric pressure?

How could we increase the vapor pressure? Think how to increase the amount of vapor present in a liquid.

ANSWER: We heat it…vapor pressure is directly related to the temperature.

1 atm

.022 atm

PHASE CHANGES

What if you’re not at 1 atm?

Pike’s Peak, CO CLC, IL

PHASE CHANGES

1.05 atm (mine) 107oC

1.00 atm (IL) 100oC

0.894 atm (Denver) 94oC

Pike’s Peak 89oC

Mt. Everest 70oC

H2O VP = 0.022 atm

PHASE CHANGES

Will foods cook faster in Denver?

No, because the BP is lower, water is cooler, cooking takes longer.

What causes the boiling point and melting point to change when a salt is dissolved in it?

COLLIGATIVE PROPERTIES

Properties that depend entirely on the number of particles dissolved in a given mass of solvent

Ex: Boiling point and melting point


Vapor Pressure Lowering Allows liquids to boil at temperatures lower than

their normal boiling point.

Vacuum Demo!!

COLLIGATIVE PROPERTIESWhy?

Because vaporization occurs at the surface and the solute is in the way….so less vaporizes, therefore VP is lower.

*depends on the # of particles of solute

= solvent

= solute


2. Boiling Point Elevation – a solution boils at a higher T than a pure solvent (like our salt lab)

Why? Boiling occurs when VP = atm P Since VP is lowered by adding salt, more E must be

added to raise VP to atm P Proportional to # of particles


Example:

Salt in H2O for cooking pasta

H2O boils at a higher T, pasta cooks faster

H2O does not boil faster


3. Freezing Point Depression – a solution freezes at a lower T than a pure solvent

Why? Particles in liquid disrupt the orderly pattern

of solid crystal, bonds cannot form as easily Must get colder to solidify Proportional to the # of particles

COLLIGATIVE PROPERTIESExample:

Melting Ice

Sand doesn’t melt ice NaCl dissolves, melts ice by

lowering fp AlCl3 better (more particles)

AGENDA 3/13/15

Check Molarity and Dilutions HW

Last minute questions before quiz

Molarity and Dilutions Quiz

AGENDA 3/16/15

Quizzes Tomorrow/Maybe Today

Back to Balancing Equations Equations in Solutions

Predicting States of matter

*** GRAB A WS FROM THE BACK TABLE***

HW: Ionic Equations


SOLUTIONS

+ - +

+- -

-

+

++ - -

NaCl (s)

OH

H

O

HH

+H

H

H

H

H

H

O

O

O

OH

H

Na+ (aq)

AGENDA 3/17/15 ST. PATTY’S DAY!!

Review Quiz

Ionic Equation Review HW Check

Ionic Reaction Demo

Energy/Phases Review

HW: Energy and Ionic Equation Worksheet

IONIC REACTIONS DEMO

I have a solution of lead (II) nitrate and lithium chloride.

Will a precipitate form?

If not, why not?

If yes, what is the precipitate that formed?

Write a complete balanced reaction including phases.

IONIC REACTION DEMO

I have a solution of sodium hydroxide and a solution of hydrogen chloride.

Will a precipitate form?

If not, why not?

If yes, what is the precipitate that formed?

Write a complete balanced equation including phases.

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PHASE DIAGRAMS

Describe the conditions of T and P where each phase is most likely to exist

Gas High T, low P

Liquid middle

Solid Low T, high P

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PHASE DIAGRAMSPhase Diagram – shows the

relationship between the 3 phases in a sealed container

84

PHASE DIAGRAMS Features: Lines of Equilibrium

On the lines, the substance exists in equilibrium between two states

At that T and P, both phases exist

1. s g2. s l3. l g

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PHASE DIAGRAMS

Features: Triple Point

One specific point at which all three phases exist in equilibrium in a sealed container

A

86

PHASE DIAGRAMS Features: Critical Point

Point past which neither liquid nor gas truly exist

An intermediate fluid phase (plasma*)

B

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PHASE DIAGRAMS

Phase Diagram for H2O

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C ONDENSED S TATES Chemistry Spring 2015. A GENDA 3/2/15 Hard Boiled Egg?? Tests Back? Learning...

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