Exam Study Guide
By: Isaac Leifert
Reaction in a Bag Lab
- hydrotropic (attracted to water)
- used with canned veggies to keep the veggies from getting mushy
- flavors pickles (salty)
Substance B= Sodium Bicarbonate (Baking Soda)
- used in baking (helps things rise)
- laundry detergent
Red Liquid= Phenol Red
- used as a ph indicator
- below seven turns yellow
- above 8 turns pink
Heating Baking Soda Lab
This video will briefly explains the lab
Why it happened
Blue Dot Questions
- What do you observe at the bottom of the test tube?
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.
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
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.
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?
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?
b. How many cubes will be needed to build a cube that measures 3 cm along each edge?
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= l x w x h (a x b x c)
Standard unit of length- meter (m)
1 centimeter (1 cm)= 0.01 m
100 cm= 1 m
Unit cube- a small cube 1 cm on each edge
Volume of Liquids Notes
*ALWAYS check the intervals or scale
Units- milliliters (mL) or cm^3
1 mL=1 cm^3
Read from bottom of meniscus
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
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
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
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
- 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
- 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)
- 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
- 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
2.1 Mass of Dissolved Salt Post Lab
- 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
ICE ICE BABY LAB
- 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
When it cools--> sulfur bonds with copper and forms copper sulfide
- 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
- 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
- antacid (basic)
- pain reliever
-aspirin (pain reliever)
-citric acid (flavor)
-sodium bicarbonate (produces gas)
2.7 CONSERVATION OF MASS
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)
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)
- 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
- 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
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
- lab groups get different density calculations for their rocks because the rock is formed by many different substances
- 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
- 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
- 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)