Science

Study Guide

Safety

Every lab:
  • Goggles must be over eyes until Mr. Leeds tells you to put them away
  • Report all accidents/spills to Mr. Leeds immediately
  • use common sense


In Case of Emergency:

  • Nurse: 2828


Safety equipment in classroom:

  • Fire extinguisher
  • Fire blanket
  • Eye wash/shower


Chemical:

  • Never taste chemicals
  • Always waft liquids
  • Never waft solids of powders
  • Avoid touching chemicals
  • always wash hands with soap and water after the lab
  • If chemicals touch your skin- flush skin with water for 1 minute and notify Mr. Leeds


Glass:

  • Hot glass and cold glass look the same: never touch test tubes
  • Never used chipped of broken glass
  • Tell mr Leeds and dispose of the broken or chipped glass
  • Never use force to remove or insert glass


Alcohol Burners:

  • Roll up sleeves
  • Put up hair (not just pulled back)
  • Never walk away from a lit burner
  • Never point the open end of a hot test tube at yourself or another person
  • Never look down into a test tube while it is being heated
  • Make sure the burner is capped and the flame is out when done with lab


End of Experiment:

  • Clean up area and materials completely (or you lose points on lab)
  • Make sure the burner is out when done using it
  • Keep goggles over your eyes until Mr. Leeds says you can take them off




Experimental Errors

1.1- Heating Baking Soda

Hole in the tubbing- gas will escape and it will not push out the water


1.4 Measuring Volume divided by displacement of water

Sand sticks to the side of the wet cylinder- volume of sand and water would be too low


1.8 The Sensitivity of a Balance

Pencil marks on the paper- will add weight


2.1 The Mass of Dissolved Salt

Not drying off the cap- water in Mi not there for Mf


2.4 The Mass of Ice and Water

Cap not sealed tightly- water will evaporate. looses weight.


2.5 The Mass of Copper and Sulfur

Hole in rubber sheet- Gas escapes


2.6 The Mass of Gas

Touch tablet after Mi- Loses Mass


3.1 Mass of Volume

Cylinder is wet when massing- increases weight


3.5 The Density of a Solid

Find volume of the Rock before mass- Mass increases


Chapter 1 labs:

1- Reaction in the bag


Red liquid:
  • Phenol Red
  • Used PH indicator
  • Below 7- turns yellow
  • Above 8- turns pink

PH Scale

  • Measures acidity
  • 0-14
  • 0-Acid
  • 7- Neutral
  • 14- Alkaline
  • Lemon juice- 1.5

Solid A

  • Calciumchloride
  • Acide- mild
  • Hydrotopic- attracted to water
  • Uses
  1. Canned Veggies- keeps from getting mushy
  2. Electrolyte- sports drinks
  3. Flavored pickles

Solid B

  • Sodium- bicarbonate (baking soda)
  • Not acidic- 8
  • Uses:
  1. Baking
  2. Cat littler
  3. Toothpaste
  4. Laundry detergent


1.1 Heated Baking Soda


Control Factor:

Definition: things that can control our outcome

Example: Unheated Baking Soda and Tea

Experimental Factor:

Heated Baking Soda and tea

Indicator:

Tea- color difference

Variables:

Something you try to measure

Independent Variable:

Causes change in dependent variable

Dependent:

Color of tea


1.2 Volume


  • Unit Measurements: cm3
  • Volume: Length x Width x Height
  • Standard Unit of Length: M (meter)
  • 1 centimeter: 0.01
  • Unit Cube: 1 cm on each side
  • Used graduated cylinder to measure volume
  • Always check the intervals of a scale
  • Units- mL (milliliters)
  • 1mL= 1cm3



1.4 Measuring volume by Displacement of Water



  • Purpose- To use displacement of water method to measure the balance of dry sand that is sand and air space


Dry Sand

50 cm3


Water

30cm3


Volume of sand and water

60cm3


Volume of sand alone

30cm3


Volume of water alone

20cm3


Fraction of sand

0.40


% of sand that is air

40%


1.6 Mass Notes


  • Beqa

- Ancient standard mass used in Egypt

-Earliest balance found in Egypt

- 7,000 years old

  • 1 Kilogrom = 1,000 grams
  • 1 kilogram = 2.2 pounds
  • Count, volume, or mass

- Elevator = count/mass

- Stadium= count

- Bridge = mass

- Bus = count

- Water Tank = volume

- train car = count

- Theatre = count

- Saucepan = volume


Mass Volume

-Beef - milk

-Bread - Butter

-Vegetables - Juice

-fruit - Soda

-fish - Water

-candy - Oils

-rice -Soups

-sugar


1.8 The Sensitivity of a Balance



  • Purpose- to observe if you mass an object repeatedly will it stay the same


Sensitivity is ∆Mass

# of yes


Penny Notes


- before 1982; 95% copper 5% zinc

-After 1982- 2.5% copper 97.5% zinc

-Copper is more expensive because of electricity

1943: Made of steel and zinc, copper needed shell casing



Chapter 2 Labs

2.1 Mass of Dissolved Salt


  • Purpose- to find out of the mass of salt decreases when salt dissolves into the water
  • 6 out of 10 groups had a decrease in mass



2.2 Histograms


  • Type of graph
  • interval- one point/middle/line to the other
  • If data falls on a line in column graph to the right
  • Take biggest and smallest before measuring


2.4 The Mass of Ice and Water


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

Mass of bottle and cap (Grams)

Mass of bottle and cap (Grams)

5.449

5.429


Mass of bottle and cap and ice (Grams)

7.243

7.131


Mi of ice (Grams)

1.794

1.702


Mass of bottle with cap and water (Grams)

7.218

7.142


MF of water (Grams)

1.769

1.713


∆M (grams)

-0.025

0.011




Condensation on the bottle- comes from water vapor in the air (humidity). when it touches cool surface of bottle it turns from a gas to a liquid


2.5 The Mass of Copper and Sulfur


Purpose- to find out if the mass will change when the substances are heated together


Mass of test tube / sheet/band

32.969


Mass of test tube/sheet/band/copper/ sulfur UNHEATED

36.178


Mi of copper and sulfur

3.209


Mass of test tube/sheet/band/copper/sulfur HEATED

36.124


MF if copper and sulfur

3.155


∆Mass

-0.054


Copper and sulfate Notes:

- melting point of copper- 1,100c

- Melting point of sulfur- 112c

- When it cools- sulfur bonds with copper and forms copper sulphide


2.6 The Mass of Gas



  • To find out if the mass will increase, decrease, or stay the same when a solid and liquid produce a gas
  • Alka-Seltzer


- Aspirin, critic acid sodium bicarbonate

- anti acid pain (produces gas)

Chapter 3 Labs

3.2 Mass of Volume




  • purpose- to see if the mass if a 1cm3 object well depends on its shape or the substance it is made of



1ST Long Cylinder

2.686 grams

1.0 cm3


2nd Long cylinder

2.741 grams

1.0 cm3


3rd Long cylinder

2.645 grams

1.0 cm3


Small aluminum cylinder

2.856 grams

1.0 cm3


Brass cylinders

8.496 grams

1.0 cm3



  • Mass and volume notes:



  1. Objects that are made of the same substance that have the same volume, will have the same MASS (regardless of their shape)
  2. The mass of an object will double if its volume doubles
  3. Objects that have the same volume are mad of DIFFERENT substances will NOT have the same mass


  • Box questions: If the mass of your brass cylinder is 8.5, what is the mass of a brass cylinder with a volume of 0.6cm3

-5.1


3.3 Density


  • A characteristic property
  • Is a specific to liquids, solids, and gas
  • Can help identify substances
  • Formula= Mass over Volume
  • Unit- cm3






Test chapter 2

1. In all four experiments from chapter 2 the common theme involved investigating changes in mass of different states of matter. You know that in all the labs there should be no change in mass because:

Law of conservation of mass


2. You are working in a class with no air conditioning, it is 90F. Your lab is to take the mass of water (65F) in a small plastic bottle with a cap on, then place the bottle in a walk-in freezer allowing the liquid to solidify, then re-mass the bottle while in the freezer. What is the possible error you should be aware of:

Condensation may form on the outside of the bottle during Mi and then freeze.


4. Test tube, rubber sheet, and rubber band- 23.681

Test tube, rubber sheet, rubber band, copper, and sulfate before reaction- 25.524

Test tube, rubber sheet, rubber band, copper, and sulfate after reaction- 25.498


Mi off the substances

Mf of the substances

∆M


-1.843g

-1.817

-0.026


Test chapter 3

1. the average thermometer is 1.25g as mercury. Volume of Mercury in thermometer is 0.0919cm3 what is the density?


1.25 divided by 0.0919 = 13.6 g/cm3


2. Necklace is 0.8Kg of platinum. Density of Platinum is 21.4, what is the volume?

21.4 = 800 = 37.4

1 v


3. Use Scientific notation and round to the tenths place:



  • Mass of solid, test tube, and water before reaction: 32.64g
  • Mass of solid, test tube, and water after reaction: 31.86g
  • Volume of Gas collected: 202 cm3
  • Density of Gas: 4 x 10 (-3)



4. The volume of gas generated by combining 1.5g of sodium bicarbonate and 6.5g of sulfuric acid is 180cm3. After the reaction the remaining aid and solid have a mass of 7.2g. what is the density of the gas produced?

0.8 = 2.1 X 10 (-3)


5. Estimate the mass of hydrogen in an empty room with the following measurements: 4 meters high, 6 meters wide, and 9 meters long. (the density of hydrogen is 8.4 x 10 (-5))

8.4 x 10 (-5) = M = 1.8 x 10 (4)

1 2.16 x 10 (3)


6. When finding the density of liquid the most accurate thing to do is

Do not pour liquid into cylinder


7. During the Density of a Gas lab the rubber tubbing is incorrectly inserted near the bottom of the bottle. This will cause:

Less Gas to collect out of the bottle


8. If the error in #7 is made it will have the following effect:

Volume decrease, density increase


9. When calculating the density of a rock it would be an experimental error to:

Find the volume prior to massing


10. When the alka seltzer tablet is mixed with water, sodiu bicarbonate within the tablet releases:

Carbon Dioxide


11. In the Density of a Gas lab a student forgets to include the foil for the Mf, the result is:

Mass of gas increases, density increases


12. Epsom salt is the marketing name for which chemical compound:

Sulfate