density_appliedchem.pptx

(1)

Warm up 11/5:

Which is heavier: a pound of

feathers or a pound of lead?

Warm up 11/5:

(2)

Warm up 11/5:

Which is heavier: a pound of

feathers or a pound of lead?

Warm up 11/5:

Which is heavier: a pound of

feathers or a pound of lead?

They have the same mass (both 1

lb)!!! BUT THEIR DENSITIES ARE

DIFFERENT!

They have the same mass (both 1

lb)!!! BUT THEIR DENSITIES ARE

(3)

Pass up your labs and HW

from yesterday

(4)

DENSITY DENSITY

_{DEFINITION: the amount of matter per unit} volume

_{Density is a measure of how tightly packed} the atoms of a substance are in a specific

space

_{DEFINITION: the amount of matter per unit} volume

_{Density is a measure of how tightly packed} the atoms of a substance are in a specific

space

(5)

Density cont.



_{Density is an INTENSIVE PROPERTY}

of matter

_{This means that a}

t a given

temperature, a substance’s density is

always the same, no matter the size

of the sample



_{Density is an INTENSIVE PROPERTY}

of matter

_{This means that a}

t a given

(6)

Density cont.



_{Each substance has a specific density}

at a certain Temperature.



_{Therefore density can be used to}

determine the identity of an

unknown substance!



_{Each substance has a specific density}

at a certain Temperature.



_{Therefore density can be used to}

(7)

Density of Vegetable Oil Density of Vegetable Oil

_{Water has a density of 1 g/mL at room} temperature.

_{It’s density would not change at that}

temperature, no matter the volume or mass of the sample.

_{Water has a density of 1 g/mL at room} temperature.

_{It’s density would not change at that}

temperature, no matter the volume or mass of the sample.

m of

Sample A sample AV of Density of sample A (D = m/V)

5 g 5 mL 5 g/ 5 mL = 1 g/mL

10.45 g 10.45 mL 10.45 g/ 10.45 mL = 1 g/ mL

(8)

Density does change with

Temperature.

Density does change with

Temperature.

_{If the temperature of a substance is increased what} happens to density?

_{The density decreases!}

_{If the temperature of a substance is decreased what} happens to density?

_{The density increases!}

_{Temperature and Density are inversely related}

_{If the temperature of a substance is increased what} happens to density?

_{The density decreases!}

_{If the temperature of a substance is decreased what} happens to density?

_{The density increases!}

(9)

Density of H

₂

O

at room

temp~ 1.0 g/

mL

Density of H

₂

O

at room

(10)

Units for Density

D =

Unit for mass: grams (g)

Unit for

volume: mL, cm3 , or L (only

for gases) Units for density

(liquids and solids)

g/mL

or g/cm3

(11)

Which color liquid do you

think has the lowest density?

Which color liquid do you

think has the lowest density?



_{The Blue Liquid!!!!}



_{If you mix liquids, they will settle}

based on their densities

_{Liquids with higher densities sink to the} bottom

_{Liquids with lower densities rise to the} top



_{The Blue Liquid!!!!}



_{If you mix liquids, they will settle}

based on their densities

_{Liquids with higher densities sink to the} bottom

(12)

WARM UP FRIDAY 11/6



_{Calculate the density of a}

cube with a length of 2 cm

and a mass of 16 g

(13)

Warm UP: Calculate the density of a cube with a length of 2 cm and a

mass of 16 g

Warm UP: Calculate the density of a cube with a length of 2 cm and a

mass of 16 g



Calculate volume first: V

_cube

= length

3



_{V = 2 cm x 2 cm x 2 cm = (2 cm)}

3

=

8 cm

3



_{Next calculate density: D=m/V}



_{D= 16 g / 8 cm}

3

= 2 g/cm

3



Calculate volume first: V

_cube

= length

3



_{V = 2 cm x 2 cm x 2 cm = (2 cm)}

3

=

8 cm

3



_{Next calculate density: D=m/V}

(14)

Warm up Tues 11/10 Warm up Tues 11/10



_{what is the mass of a cylindrical}

object with a density of 10.5 g/mL

and the following dimensions? h=

3 cm , r= 2 cm (V= r

2

h)



_{what is the mass of a cylindrical}

(15)



_{Go over lab expectations}



_{Finish question 10-14}



_{Review worksheet}



_{Go over lab expectations}



_{Finish question 10-14}

(16)

LAB PURPOSE- paragraph form LAB PURPOSE- paragraph form

_{Look at the introduction of the lab to help} you!

_Discuss:

_{What density is. (how it is defined etc)} _{How to calculate density}

_{What will be done in the lab (the objectives)}

_{What methods will be used to find volume and} density

_Discuss:

_{What methods will be used to find volume and}

(17)

Conclusion Paragraph form Conclusion Paragraph form

_{Readdress your purpose}

_{Tell me the identity of your unknowns.}

_{Discuss the accuracy of your results (refer back to the % error}

calculations)

_{Describe what could have caused the error in your results.} _{How did your results compare to the other groups (for the}

irregular solid)?

_{Which method do you think is most accurate for finding volume?}

(water displacement or measuring the dimensions?) _{Readdress your purpose}

calculations)

irregular solid)?

(18)

Warm up Tues 11/10 Warm up Tues 11/10



_{what is the mass of a cylindrical}

object with a density of 10.5 g/mL

and the following dimensions? h=

3 cm , r= 2 cm (V= r

2

h)



_{what is the mass of a cylindrical}

(19)



_{Finish question 6-14}



_{Review worksheet}



_{Finish question 6-14}

(20)

LAB PURPOSE- paragraph form LAB PURPOSE- paragraph form

_Discuss:

_{What methods will be used to find volume and} density

_Discuss:

_{What methods will be used to find volume and}

(21)

Conclusion Paragraph form Conclusion Paragraph form

_{Readdress your purpose}

calculations)

irregular solid)?

(water displacement or measuring the dimensions?) _{Readdress your purpose}

calculations)

irregular solid)?

(22)

Warm up 11/11 Warm up 11/11



_{Calculate the mass of a bar of}

cadmium (d=8.65 g/cm

3

) with

the following dimensions: 2 cm

x 1 cm x 5 cm



_{Calculate the mass of a bar of}

(23)

Today… Today…



_{Practice with passive voice}



_{Go over the density packet}



_{Complete Density 3}



_{Density Worksheet 2 is homework}



_{Practice with passive voice}



_{Go over the density packet}



_{Complete Density 3}

(24)

Warm up: 11/12 Warm up: 11/12

_{A graduated cylinder is filled with 25 mL of} water. An oddly shaped object is placed in the graduated cylinder and the water level rises to 30.5 mL. The mass of the object is 11 g.

_{What is the volume of the object?} _{What is the mass of the object}

_{A graduated cylinder is filled with 25 mL of} water. An oddly shaped object is placed in the graduated cylinder and the water level rises to 30.5 mL. The mass of the object is 11 g.

(25)

Today… 8th period

_{Pass up Density worksheet 2!} _{Thermochemistry notes}

_{Bonus Option}

_{Pass up Density worksheet 2!} _{Thermochemistry notes}

(26)

Warm up: 11/3 Warm up: 11/3



_{Is energy released or}

absorbed during an

endothermic process?



_{Is energy released or}

absorbed during an

(27)

Introduction to Thermochemistry Introduction to Thermochemistry

_{Thermochemistry is the study of energy changes} that occur during chemical reactions and changes in state.

_{Chemical potential energy: the energy}

contained in the chemical bonds of a substance. _{During chemical reactions, energy changes occur}

_{Energy changes occur as either heat transfer,} work, or both

_{Thermochemistry is the study of energy changes}

that occur during chemical reactions and changes in state.

_{Chemical potential energy: the energy}

contained in the chemical bonds of a substance.

_{During chemical reactions, energy changes occur} _{Energy changes occur as either heat transfer,}

(28)

Example: The fuel in a car’s engine Example: The fuel in a car’s engine

_{When fuel is burned (chemical rxn) in a car engine,} the chemical potential energy (of the fuel) is

released and transformed into useful work.

_{This is what is used to propel the car.}

_{At the same time heat is also produced, making} the car engine extremely hot.

_{Chemical Potential energy}__{heat energy and work}

_{When fuel is burned (chemical rxn) in a car engine,}

the chemical potential energy (of the fuel) is released and transformed into useful work.

_{This is what is used to propel the car.}

_{At the same time heat is also produced, making}

the car engine extremely hot.

(29)



_{The law of conservation of Energy:}

Energy is neither created nor destroyed

during any chemical or physical process

_{If the energy of the SYSTEM increases, the} energy of the SURROUNDINGS must

decrease

_{If the energy of the SYSTEM decreases, the} energy of the SURROUNDINGS must

increase.

_{Heat lost = Heat gained}



_{The law of conservation of Energy:}

Energy is neither created nor destroyed

during any chemical or physical process

_{If the energy of the SYSTEM increases, the} energy of the SURROUNDINGS must

decrease

_{If the energy of the SYSTEM decreases, the} energy of the SURROUNDINGS must

increase.

(30)

HEAT

_{Heat: energy that transfers from one object} to another because of a temperature

difference between them

_{Heat always flows form a warmer object to} a cooler object.

_{Heat transfer will continue to occur until} the two materials are both at the same

temperature

_{Endothermic vs Exothermic}

_{Heat: energy that transfers from one object} to another because of a temperature

difference between them

_{Heat always flows form a warmer object to} a cooler object.

_{Heat transfer will continue to occur until} the two materials are both at the same

temperature

(31)

SPECIFIC HEAT

CAPACITY

SPECIFIC HEAT

CAPACITY



_{The transfer of heat affects substances}

differently (think about the beach: sand vs water)



_{Measuring heat transferred to and}

absorbed by a substance under conditions

of constant pressure yields specific heat

capacity.



_{The transfer of heat affects substances}

differently (think about the beach: sand vs water)



_{Measuring heat transferred to and}

absorbed by a substance under conditions

of constant pressure yields specific heat

(32)

SPECIFIC HEAT

CAPACITY

SPECIFIC HEAT

CAPACITY



_{Specific heat: The quantity of heat required}

to raise 1 gram of a substance by 1°C or 1 K.



_{Symbol: Cp}

_{The p symbolizes that the measurements}

were taken under constant pressure.



_{Units = Joules/ gram °C}

_

_(J/g°C)



_{Specific heat: The quantity of heat required}

to raise 1 gram of a substance by 1°C or 1 K.



_{Symbol: Cp}

_{The p symbolizes that the measurements}

were taken under constant pressure.

(33)

Materials with High Specific Heats Materials with High Specific Heats



_{Resist changes in temperature}



_{It takes longer for a substance with a}

high specific heat to both increase

AND decrease in temperature.



_{They are good insulators}



_{Resist changes in temperature}



_{It takes longer for a substance with a}

high specific heat to both increase

AND decrease in temperature.

(34)

High Specific Heat High Specific Heat



_{Materials with a high specific heat can}

absorb a large amount of heat before

their temperature increases.



_{The higher a material’s specific heat,}

the more heat which must be

absorbed before it increases in

temperature.



_{Materials with a high specific heat can}

absorb a large amount of heat before

their temperature increases.



_{The higher a material’s specific heat,}

(35)

Low Specific Heat

_{What does it mean to have a low specific heat?} _{More susceptible to changes in temperature}

(change temperature more readily)

_{It takes less time for a substance with a low}

specific heat to both increase AND decrease in temperature.

_{Less heat is required to be absorbed before}

the substance increases in temperature.

_{They are good conductors.}

_{What does it mean to have a low specific heat?} _{More susceptible to changes in temperature}

(change temperature more readily)

_{It takes less time for a substance with a low}

specific heat to both increase AND decrease in temperature.

_{Less heat is required to be absorbed before}

the substance increases in temperature.

(36)

Sample Cp values

_{Metals have low specific heat values which allows them}

to heat up with little added energy.

_{Metals are examples of good thermal conductors.}

 _Iron _{0.449 J/g°C}  Copper 0.385 J/g°C

 _{Platinum 0.133 J/g°C}

_{Water has a relatively high specific heat 4.184 J/g °C} _{Metals have low specific heat values which allows them}

to heat up with little added energy.

_{Metals are examples of good thermal conductors.}

 _Iron _{0.449 J/g°C}  Copper 0.385 J/g°C

 _{Platinum 0.133 J/g°C}

(37)

Questions: Questions:



_{Which would heat up faster, 5.00 grams of}

iron or 5.00 grams of water?



_{The iron- bc its specific heat capacity is less.}



_{Which would cool down faster, 5.00 grams of}

iron or 5.00 grams of water?



_{The iron again!- its low specific heat}

capacity allows it to cool faster



_{Which would heat up faster, 5.00 grams of}

iron or 5.00 grams of water?



_{The iron- bc its specific heat capacity is less.}



_{Which would cool down faster, 5.00 grams of}

iron or 5.00 grams of water?



_{The iron again!- its low specific heat}

(38)

Questions: Questions:



_{Which is a better thermal}

conductor?



_{Iron, metals are great conductors of}

heat



_{Which is a better insulator?}



_Water



_{Which is a better thermal}

conductor?



_{Iron, metals are great conductors of}

heat

(39)

MEASURING HEAT and SPECIFIC HEAT

_{Must use a calorimeter.} _{Find the change in}

temperature:

_{ΔT = (delta T)}

_{change in temperature in} °C

_{T = T final – T initial}

_{Must use a calorimeter.} _{Find the change in}

temperature:

_{ΔT = (delta T)}

_{change in temperature in}

°C

(40)

q= energy (HEAT) required

_{units: Joules (J) or Calories (cal)} _{+q= endothermic, -q= exothermic}

m= mass of the sample in grams Cp= Specific heat

_units:_J/g°C

ΔT= change in temperature

_Units:_°C

q= energy (HEAT) required

_{units: Joules (J) or Calories (cal)} _{+q= endothermic, -q= exothermic} m= mass of the sample in grams