Exam Study Guide

december 18 & 19

Lab Safety

  • See worksheet


Reaction in a Bag Lab

  • Purpose= to record the observations that occur when multiple chemical substances are combined and to use my observations to understand the reactions of the chemicals

  • Exothermic= heat
  • Endothermic= cold
  • Error= hole in bag (you wouldn't know a gas was being produced)

  • Red liquid= phenol red
-pH indicator
-below 7 turns yellow/ above 8 turns pink
  • pH scale
-measures acidity

-0-14

-Acid= 0 (lemon juice is 1.5)

-Neutral= 7

-Base= 14 (tums is 10)


  • Solid A= calcium chloride
-acidic and hydrotropic (absorbs water)

-used in canned good to keep from getting mushy

-salty taste


  • Solid B= sodium bicarbonate
-baking soda

-not acidic

-used in baking, toothpaste, and detergent




Scholar Reaction In The Bag Inquiry Demonstration and Lab Activity

CHAPTER 1

1.1 Heating Baking Soda Lab

  • Purpose= To observe and record the reaction that occurs when baking soda is heated

  • Condensation at the top of the test tube comes from hot droplets of water released by the baking soda that touch the cool top of the test tube and turn back into a liquid
  • Gas produced by the heated baking soda leaves the test tube and runs through the rubber tube which pushes gas into the bottle so water must leave
  • The heated and unheated baking soda are different because the tea is different color when separately mixed with both

  • Control group=unheated test tube
  • Experimental group=heated test tube
  • Indicator=tea
  • Variable=a category you try to measure
-Independent- causes a change in the dependent (temperature)
-Dependent- (color of the tea)
  • Control factors= using the same amount and type of tea, same amount of baking soda, same size test tubes
  • Experimental errors= hole in tubing or loose stopper would make us not see the gas fill the bottle

  • There is less condensation from the baking soda because it cannot produce more than itself



  • Baking soda is used in baking b/c it releases a gas that makes bater rise


Lab 1.1 Heating Baking Soda

1.2 Volume notes

  • unit of measurement= cm^3 (cubic centimeters)
  • Volume= l times w times h
  • standard unit of length= m (meter)
  • 100 cm = 1m
  • unit cube= small cube 1 cubic centimeter on each edge
  • graduated cylinder measures volume *check intervals and read bottom of meniscus
  • 1mL= 1cm^3
  • Always go one more than given interval

BQ's 3-13

3. 50 cubic centimeters of water fill a 50mL grad. cylinder

4. Box a could have a greater volume than box b even if its height is smaller...bigger length and width

5. 25.0 cm^3 raised to 32.0cm^3 after a stone was added...stone is 7cm^3

6a. How many cubes are needed to build a cube 2cm along each edge? 8

6b. How many cubes are needed to build a cube 3cm along each edge? 27

6c. Volume of a= 8cm^3

Volume of b=27cm^3

7. 30 by 15 by 10 vs. 25 by 16 by 15... which one is greater? second one

8. why are the divisions not spread out equally on a cone shaped graduated cylinder? the cone is narrower at the bottom

9. you can estimate one more than the given measurement

10 & 11. measurements

12. 12cm= 11.5-12.4

12.0= 11.95-12.04

12.00=11.995-12.004

13. advantage to tall/ narrow graduated cylinder rather than short/ wide is the lines are farther apart making it easier to read


1.3 Balance Notes

Check that pan is clean and dry

zero balance before each massing

never switch pans

hold by red bar only


1.4 Measuring Volume by Displacement of Water

  • Purpose: To use the displacement of water method to measure the volume of dry sand that is sand and air space
  • know calculations: sand alone, air space, fraction of air that is sand
  • experimental error
-sand sticks to sides of wet cylinder
-pour water into sand (water sits on top of sand b/c air space does not allow it to filter down)


  • no matter how much you begin with there will always be 40% air space


BQ #14-17

14. volume of a marble is 1.0cm^3... how many are needed to fill a cylinder to the 100cm^3 mark? less than 100 b/c of air space

15. know calculations

16. how do you measure the volume of sugar? find a substance it won't dissolve in (oil)

17. how do you measure the volume of a cork stopper? find volume of weight and subtract after displacement of water method




Big image
Lab 1-4 Measuring Volume By Displacement

1.6 more mass notes

  • beqa- ancient standard mass in Egypt
  • earliest balance was found in Egypt (approx. 7,000 years old)
  • standard unit of mass= grams (g)
-1 kilo (kg)= 1,000g

-1kilo= 2.2 pounds


BQ #18-21

18. balance only directly tells us mass (not substance)

19. use count in stadiums, use mass in bridges, use volume in fish tank

20. in grocery stores volume measures water, juice, sauce and mass measures apples, sugar, orange

21. divide you wight by 2.2 to find your mass in kilograms

1.8 Sensitivity of a Balance

  • Purpose : to determine if you mass the same object repeatedly will the mass remain the same. Also, to find out how different the masses of 2 objects must be for our balance to detect the difference.
  • Know calculations: ΔM, sensitivity
mass of a single square= m of 20x20/400

ΔM= Mf-Mi

Sensitivity= ΔM/ # of yes's



  • Mass of a penny before 1982: 95% coper, 5% zinc; After 1982: 2.5% copper, 97.5% zinc
  • Reason was copper was used for computers
  • 1943: made of steel and zinc b/c copper was needed for shells of wooden bullets



  • Sensetivity of a balance= the lights mass that you can expect the balance to detect
  • The margin of error when you mass something



BQ #23, 26, 27

23. know formulas

26. find average of volumes to find the most accurate

27. to see if someone made an incorrect measurement find the range and see if anyone goes above of below the sensitivity (0.02)

REVIEW QUESTIONS

29. the liquid used in the displacement method does not affect the volume

30. 5 cubes along one edge, 4 along one edge, 6 horizontal, with an empty space at the top.

a. if height of space is half the length of an edge of a cube... 5x4x6.5= 130cm3

b. if height of space is 0.23 of the length of an edge of a cube...5x4x6.23= 124.6cm3

31. l times w times h

34. selling oil by gallon is more efficient and selling coal by ton is more efficient

35. solids= mass, liquid=volume

36. the volume of an aluminum cube with edges that are 10cm long is 1000cm3

the mass of aluminum cube when one cm3 is 2.7g is 2700g

37. mass of a gold bar 1x2x25 when cm3 has the mass of 19g is 950


TEST 1

1. review questions, bq's, calculations

3. all conversions in 1.4

-what is the volume of water that fills the air spaces in the dry sand? volume of air

-what is the volume of water that does not fill the air spaces in the sand? water-air



1. heating baking soda? how would a hole in rubber tubing affect their understanding of the lab?

the gas will leak out, and they would not know it was being generated from the backing soda b/c the water will not be pushed out

2. reaction in a bag? how would hole in zip lock bag affect their understanding of the lab?

the bag will not inflate b/c the gas leaks out so they would not see a reaction

3. we were assigned different amounts of dry sand to prove that it is always about 40% air


3. measure cm with cm side 0.00


1. by using the range 0.003 and 0.007 there is a guarantee the balance could detect it


CHAPTER 2

2.1 Mass of Dissolved Solids

Purpose: To determine if the mass of salt decreases when salt dissolved in water


errors: not drying off the cap- water in Mi not there for mf

not shaking long enough- undissolved

cap not on tightly- spillage


BQ #1-6

1. ignore

2. it is important to do Mf-Mi rather than Mi-Mf b/c you would get i different answer

3. you do not need to know the mass of salt and water separately, just need to know Mf

4. if you evaporate water to get salt back there will be the same amount of salt as you started with, we know this b/c it does not rain salt

5. you cannot detect a change in mass less the 0.02

6. ignore



2.2 Histograms

used in financial, weather


graph to column on the right if its on the line


BQ #8-11

ignore

2.4 The Mass of Ice and Water

Purpose : to determine if the mass of ice will increase, decrease, or stay the same when it melts

condensation on bottle comes from water vapor in the air when it touches the cool surface and turns to liquid

errors:

not wiping off condensation- gain mass

bottle is wet during Mi- lose has

shaking bottle- lose mass


2.5 The Mass of Copper and Sulfur


  • Purpose: To find if the total mass increases, decreases, or stays the same when copper and sulfur are heated together
  • yellow smoke is from water in sulfur that turns to vapor (gas) and rises in test tube
  • when it cools sulfur bonds w/ copper, forms copper sulfide
  • errors: hole in rubber sheet, sheet is not on tight enough- gas escapes
  • sheet=flexibility
  • BQ'S 15-16
15. ignore

16. if a change from 36.50 to 36.48 occurs it is reasonable to say it remained the same b/c it is under the sensitivity of a balance

to increase confidence we should redo lab




2.6 The Mass of a Gas

  • Purpose: to determine if the mass will increase, decrease, or stay the same when a solid and liquid produce a gas

  • errors: touch tablet after Mi and cap is wet, water in pan during Mi- decrease
  • Alkaseltzer= antacid and pain relief
  • Ingredients= asprin, citric acid, sodium bicarbonate (produce gas)


2.7 and 2.8 Conservation of Mass and Laws of Nature

Closed system- a space where nothing can enter of leave


law of conservation of mass= in a closed system mass all remain constant, regardless of the actions or the process inside the closed system


BQ'S #17, 19-23

17. if it is an open system there is no contradiction

19. "What comes up must come down" is a law of nature b/c there is gravity

20. blue sky is a law of nature on earth

21. a reason for using a lid when working with water is to prevent condensation

22. ignore

23. if you massed the entire apparatus in 1.1 heating baking soda lab the mass would be the sam b/c baking soda gas could not escape (maybe some water would evaporate)

Chapter 2 test

  • Possible error in Mass of Gas that would cause loss in mass- not closing cap all the way (gas would escape throughout the lab and loose mass)
  • Possible error in Mass of Copper and Sulfur that would cause loss in mass- hole in rubber sheet (gas would escape and cause a lose in mass)
  • Possible error in Ice and Water that causes gain- condensation was not wiped off (water would be added to outside, Mf would not be there)
  • Start over lab if condensation forms on inside of bottle
  • No change in mass= conservation of mass
  • Hot to cold with condensation would cause frozen on outside
  • Salt does not evaporate
  • Calculations to find Mf, Mi, and delta m
  • Percentage of change= delta m/ mi = x/100
  • histogram
  • know what goes between each interval


CHAPTER 3

3.1 Characteristic properties

  • Substance tells u what it is made of ex: steel
  • Substance does not tell us what it is made of ex: heavy, blue

3.2 Properties of Substances and Properties of Objects

  • Purpose: to determine if the mass of a 1cm3 object willd epend on its shape or the substance it is made of
  • Depends on substance
  • errors:
  • using the same long cylinder twice
  • Cylinder is wet when massed- increase
  • Water splashes out of cylinder- decrease


Mass and volume notes

  1. objects made of the same substance that have same volume will have the same mass regardless of their shape
  2. mass of an object would double if is volume doubles
  3. objects that have the same volume but are made of different substances will not have the same mass


BQ 3-5

3. aluminum cylinder with volume of 1cm^3 is 2.7 g... mass of an aluminum cylinder with volume of 3cm^3 is 8.1g

4. ignore

5. if samples of brass and alumni both have the same mass... aluminum will have a greater volume

3.3 Density

  • characteristic property
  • can help identify substance


BQ 6

6. wheels in a lot depends on number of vehicles

wheels per automobile does not depend on number of automobiles

number of wheels per automobile is a characteristic property b/c they are categorized based on # of wheels

REMEMBER TO WRITE LABEL IN GRAPHS ex: (g)

Big image

3.5 Density of a Solid

  • purpose: to utilize density to determine if 3 metal objects are made of the same substance
  • lxwxh=v
  • different densities for rock b/c rocks are made of different substances being compressed together, different substances have different densities
  • errors: water splashes out of graduated cylinder, find volume of rock before mass (adds mass), paint chips off object (decrease mass)


ignore BQ's


3.6 The Density of a Liquid

  • Purpose: to use density to compare 2 liquids to determine if they are the same substance
  • Errors: not rinsing cylinder between substance, cylinder is not remised, outside of cylinder is wet during Mi
  • Magnesium sulfate= epsom salt


3.7 The Density of a Gas

  • Purpose: to produce and collect a gas in order to accurately determine the density of a gas
  • Errors: make sure hand seals bottle (air bubble), don't touch tablet after Mi, spill water when finding volume of water


19. density does not depend on how much of a substance

22. gas dissolving slightly in water would decrease volume (tubing must be at top of bottle



***1 kilo=1,000g

***1 m= 100cm

CHAPTER 3 TEST

  • D= m/v
  • density of gas calculation
  • scientific notation
  • room
  • delta m is different than mass of gas (can have negative)
  • volume and mass in grad. cylinder = most accurate, do not have to transfer liquid
  • Rubber tubing in bottom= less gas collect in bottle
  • ^ volume decrease, density invrease
  • Mass before volume in rock
  • Alka seltzer releases carbon dioxide
  • Forget foil for Mf= mass of gas increases, density increases
  • epsom salt= magnesium sulfate
  • graphs