Exam Study Guide

By: Isaac Leifert

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Reaction in a Bag Lab

Purpose

The purpose of this lab was to record the observations that occur when multiple chemical substances are combined and to use my observations to understand the reactions of the chemicals.


Materials

Substance A= Calcium Choride


  • acidic
  • hydrotropic (attracted to water)
  • used with canned veggies to keep the veggies from getting mushy
  • electrolytes
  • flavors pickles (salty)

Substance B= Sodium Bicarbonate (Baking Soda)

  • basic
  • used in baking (helps things rise)
  • toothpaste
  • laundry detergent

Red Liquid= Phenol Red

  • used as a ph indicator
  • below seven turns yellow
  • above 8 turns pink

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Heating Baking Soda Lab

Purpose

The purpose of this lab was to observe and record the reaction that occurs when baking soda is heated.


This video will briefly explains the lab

Lab 1.1 Heating Baking Soda

Why it happened

The gas leaving the test tube comes from the baking soda. The moisture at the top of the test tube comes from hot gas. When it touches the cooler top of the test tube, it turns back into a liquid. The baking soda in the heated test tube did not mix with the tea because it was no longer baking soda. When it was heated, its chemical properties were changed, thus it became a different substance. The color of the tea was darker in the test tube with heated baking soda while in the test tube with the unheated baking soda, the color was lighter because the substances mixed.

Blue Dot Questions


  1. What do you observe at the bottom of the test tube?

Nothing happened.


2. What do you observe near the top of the test tube?

There is condensation and water is dripping down the sides.

3. What do you observe in the inverted bottle?

The water is emptying into the plastic container and there is more gas in the bottle.

4. Where do you think the gas came from?

The heated baking soda.

5. Where did the droplets on the test tube come from?

The gas that was being produced by the baking soda.

6. Describe the color of the liquid in each test tube.

In the heated test tube, the tea didn't change color because the baking soda was solid and it didn't mix while the other non-heated test tube is lighter and slightly cloudy because the baking soda mixed.

7. Are the two white powders the same substance? What is your evidence?

No, the two white powders are not the same substance because one was heated and its chemical and physical properties were changed. This was shown by the fact that it was solid and that it didn't turn the tea the same color.

Extra Information

Experimental Group- heated test tube


Control Group- unheated test tube

indicator- tea (showed that the heated baking soda is no longer just baking soda)


Variable- a category that you try to measure

Independent Variable- causes a change in the dependent variable (temperature/heat)

Dependent Variable- color of the tea


Control Factors- things that we can control:

  • same type of tea
  • same amount of baking soda
  • same amount of tea
  • same size test tube
  • same stirring time

Extra Question

Is the amount of condensation that forms at the top of the heated test tube more or less than the amount of baking soda being heated?

The amount of condensation is less than or equal to the amount of baking soda being heated because the condensation comes from the baking soda and it cannot produce more than itself.

Box Questions

1. Why do you think baking soda is used in cooking?


It helps make things rise (produces gas when heated).

3. How many cubic centimeters of water are required to fill a graduated cylinder to the 50.0-mL mark?

50 cubic centimeters of water.

4. Rectangular box A has a greater volume than rectangular box B but the length of box A is less than the length of Box B. How is this possible?

The width and height of box A is larger than box B.

5. Adding a stone to a graduated cylinder containing 25 cubic centimeters of water raises the water level in the cylinder to the 32 cubic centimeter mark. What is the volume of the stone?

7 cm^3.

6. A student has a large number of cubes that measure 1 cm along each edge.

a. How many cubes will be needed to build a cube that measures 2 cm along each edge?

8

b. How many cubes will be needed to build a cube that measures 3 cm along each edge?

27

c. What is the volume, in cubic centimeters, of each of the cubes in (a) and (b)?

(a)= 8 cm^3

(b)= 27 cm^3

7.One rectangular box is 30 cm long, 15 cm wide, and 10 cm deep. A second rectangular box is 25 cm long, 16 cm wide, and 15 cm deep. Which box has the larger Volume?

Box 2 has the larger volume.

8. Figure A shows a cone-shaped graduate used for measuring the volume of liquids. Why are the divisions not equally spaced?

Because as the height increases, the surface are increases therefore more water can fit into a smaller space.

Volume

Volume Notes

Unit of measurement- cm^3 (cubic centimeters)


Volume= l x w x h (a x b x c)

Standard unit of length- meter (m)

1 centimeter (1 cm)= 0.01 m

centi=100

100 cm= 1 m

Unit cube- a small cube 1 cm on each edge

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Volume of Liquids Notes

Use a graduated cylinder to measure volume.


*ALWAYS check the intervals or scale

Units- milliliters (mL) or cm^3

1 mL=1 cm^3

Read from bottom of meniscus

Triple Beam Balance Notes

  1. check if pan is clean/dry
  2. always zero balance before each massing (push all riders to zero [left] and use adjustment knob if needed)
  3. Never switch pans
  4. Pick up balance by red bar only
  5. Don't zero balance when done


Lab Safety

Safety Notes

For Every Lab:


Goggles must be kept OVER YOUR EYES until Mr. Leeds says to put them away

**even if you are already finished and cleaned up**

Report ALL accidents/spills to Mr. Leeds immediately


In Case of Emergency:

Nurse: ext: 2828


Safety equipment in classroom:

  • Fire extinguisher
  • Fire Blanket
  • Eye wash/shower


Chemicals:

Never taste chemicals (even if they look yummy!)

Always WAFT liquids to detect odor

NEVER WAFT SOLIDS/POWDERS!

Avoid touching chemicals

Always wash hands with soap and water after lab

If chemicals touch skin: flush skin with water for 1 minute AND notify Mr. Leeds


Glass:

Hot glass and cold glass look the same

Never use chipped or broken glass

-tell Mr. Leeds and dispose of broken glass in proper trash

Never use force to remove or insert glass


Alcohol Burners:

Roll up sleeves, put UP long hair, NOT just pull back (or you cannot do lab)

Never walk away from a lit burner

Never point the open end of a hot test tube at yourself or someone else

Do not look down into a test tube/beaker while it is being heated

Make sure burner is capped and flame is out when done


End of Experiment:

CLEAN-UP AREA & MATERIALS COMPLETELY!!!! (Or you LOSE points)

Make certain that burner is out if one was used

Keep goggles on (over eyes) until Mr. Leeds says to put them away

LBS TO KG AND KG TO LBS

  • pounds to kilograms (x/2.2)
  • kilograms to pounds (x*2.2)


MEASURING VOLUME BY DISPLACEMENT OF WATER LAB

EXPERIMENTAL ERRORS

  • sand sticks to sides of wet cylinder-->volume of sand and water would be too low
  • pour water into sand--> water sits on top of sand because the air spaces don't allow water to filter down


Extra Question

Why were lab groups instructed to use different amounts of sand? (What was the purpose?)

  • It didn't matter how much dry sand you began with, each group has approximately 40% air space in the sand.



1.6 Notes (Mass: The Equal-Arm Balance)

  • Beqa- ancient standard mass used in Egypt
  • Earliest balance found in Egypt (approx. 7,000 yrs old)

MASS

  • standard unit is grams
  • 1 kilogram (kg)= 1,000 g
  • 1 kg= 2.2 lbs


Lab 1.8 Sensitivity of a Balance

1.8 Post Lab

Sensitivity of Balance

  • the lightest mass that you can expect the balance to detect
  • + or - the margin of error when you mass something

Mass of Penny (Penny Notes)

  • Before 1982: 95% copper and 5% zinc
  • After 1982: 2.5% copper 97.5% zinc
  • In 1943: made of steel and zinc

-Copper was needed for shell casings (bullets)

-A 1943 copper penny has sold for $82,500

CHAPTER 2

2.1 Mass of Dissolved Salt Post Lab

Experimental Errors

  • Not drying off the cap--> water in Mi not there for Mf
  • remove cap before Mf--> spillage/leakage
  • not shaking long enough--> not dissolved
  • spill salt when pouring into bottle
  • cap not on tightly--> spillage/leakage


HISTOGRAMS

ICE ICE BABY LAB

Experimental Errors

  • not wiping off condensation--> gain mass
  • bottle is wet during Mi--> lose mass
  • shaking bottle--> lose mass


THE MASS OF COPPER AND SULFUR

2.5 Post Lab

Yellow Smoke- water in sulfur turns to vapor (gas) and rises in test tube


When it cools--> sulfur bonds with copper and forms copper sulfide


Experimental Errors

  • Rubber sheet has a hole--> gas could escape
  • sheet is not on tight--> gas could escape
  • sulfur sticks to sides of test tube--> doesn't react
  • clean pan between Mi and Mf


2.6 THE MASS OF A GAS LAB

Post Lab

Experimental Errors:

  • cap is not on tight or you do not put it on quick enough--> lose mass and gas
  • water in pan during Mi-->Lose mass (not going to be there later) (must start over if this happens)
  • cap is wet during Mi--> lose mass (not going to be there later)
  • touch tablet after Mi--> lose mass (comes off on hand) (alkaseltzer tablet dissolves

Alkaseltzer:

  • antacid (basic)
  • pain reliever
  • Ingredients:

-aspirin (pain reliever)

-citric acid (flavor)

-sodium bicarbonate (produces gas)

2.7 CONSERVATION OF MASS

Notes

Closed system- a space where nothing can leave or enter

LAW OF CONSERVATION OF MASS:

In a closed system mass will remain constant, regardless of the actions of the processes inside the closed system

20*C= Room Temperature (*=Degrees)

CHAPTER 3

Characteristic Properties

Property of an Object: does not tell you what it is made out of

Property of a Substance: this helps you identify what the object is made out of


3.2 Mass and Volume Lab (rods)

EXPERIMENTAL ERRORS:

  • cylinder is wet when you mass it--> add mass
  • water splashes out of graduated cylinder--> volume will be less
  • mass/volume same cylinder twice

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)

-EX: long aluminum cylinder and short aluminum cylinder

2. the mass of an object will double if its volume doubles

3. objects that have the same volume but are made of different substances will not have the same mass

-EX: aluminum and brass cylinders

3.3 Density Notes

  • D=M/V


3.5 The Density of a Solid

  • Histogram shows that cube 1 and slab are most likely the same substance and cube 2 is a different substance

The Rock:

  • lab groups get different density calculations for their rocks because the rock is formed by many different substances

Experimental Errors:

  • Water splashes out of graduated cylinder
  • take volume of rock before mass--> M goes up so D goes up
  • paint chipped off object--> loss in mass
  • measuring same side twice


3.6 THE DENSITY OF A LIQUID LAB

Post Lab 3.6

Experimental Errors:
  • not rinsing out cylinder between substances--> different density
  • don't re-mass cylinder for first mass (empty)--> different amounts of water in cylinder
  • outside of cylinder is wet during mass empty--> comes off by evaporation or on hands
  • dry cylinder after you mass it empty--> lose mass

Magnesium Sulfate= Epsom Salt

Post Lab 3.7

Experimental Errors:


  • if you put foil back before Mf (M goes up and D goes up)
  • if you touch the tablet after Mi (M goes up and D goes up)
  • If you break the surface of the water with the bottle (V goes up and D goes down)
  • stopper is not on tight (lose gas)
  • spilling water when finding volume of bottle (V goes down and D goes up)