SAFETY NOTES AND QUIZ
- 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/sills to Mr. Leeds immediately
- USE COMMON SENSE ALWAYS
2. In Case of Emergency
- Nurse extension: 2828
3. Safety Equipment in Classroom
- Fire extinguisher
- fire blanket
- eye wash station/ 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
6. 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
7. End of Experiment
- CLEAN-UP AREA AND 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
Fill in the blank:
- Test the odors of liquids by wafting them under your nose
- If something spills or breaks the first thing you do is tell Mr. Leeds
- You should wash your hands with soap and water after handling all chemicals
- Never use force to remove or insert glass
- Before you leave for class, your lab area must be completely clean
- Capping the alcohol burners puts out the flame because fire needs oxygen
- You must keep your goggles on until Mr. Leeds says to remove them
- 2828 is the extension for the Nurse in case of an emergency during class
True or false:
- You should report all accidents to Mr. Leeds at the end of class- False
- You should never throw broken glass into the regular trash- true
- If you get any chemicals on your skin you should flush your skin with water and tell Mr. Leeds- true
- You can take your goggles off as soon as you finish the lab- false
- hot glass looks different than cold glass- false
- It is ok to use a cracked test tube as long as you are careful- false
- The emergency blanket is used if someone really needs to take a nap- false
- It is ok to put your goggles up on your forehead when you clean up- false
- List three important safety tips when working with an alcohol burner (other than wear goggles)
-put your long hair in a ponytail
-never walk away from a lit burner
-roll up long sleeves
- List three safety precautions you should take when using chemicals (other than wearing goggles)
-to smell a liquid chemical, always waft the smell
-never waft a solid or powder chemical
-if a chemical touches your skin, flush that body part under the water for one minute and call over Mr. Leeds
- List one thing you should do at the end of every experiment or you will lose points
-clean up your area
- List three pieces of safety equipment located within the classroom
-eye wash/ shower
- What is the emergency blanket used for
- you wrap the emergency blanket around anything that is on fire, and the chemicals on the blanket will put out the fire.
REACTION IN A BAG
- What reaction does Solid A cause when mixed with a liquid
- the formula becomes hot
- What reaction does Solid B cause when mixed with a liquid
- the formula becomes cold
- What reaction does Solid A + Solid B cause when they are both mixed with a liquid
- When the solids are dissolved the bag inflates
- What does exothermic reaction mean
- hot reaction
- What does endothermic reaction mean
- cold reaction
-uses: baking, cleaning, toothpaste
-hydrotropic (attracted to water)
-uses: canned veggies (keeps from getting mushy), electrolytes (sports drinks), flavors pickles (salty)
-used as a ph idicator
-below 7 turns yellow, above 8 turns pink
-goes from 0-14
-0 (acid)- 7 (neutral)- 14 (base)
-lemon juice: 1.5
Heating Baking Soda
- There was no change at the bottom of the heated test tube.
- There is condensation at the top of the heated test tube when it is heated.
- The inverted bottle loses water when the test tube is heated.
- The gas from the second experiment came from the baking soda.
- The droplets on the test tube in the second experiment also came from the baking soda.
- The condensation comes from hot gas touching a cooler surface at the top of the test tube and it turns back into liquid droplets.
- THINK BASIC: if the two liquids aren't the same color they had different substances in them.
- The heated beaker is different because, it is not same color as the unheated beaker.
Other information to know:
- control group- unheated test tube
- indicator- tea (indicated that the solids are different)
- experimental group- heated test tube
- variable- something you try to measure
- independent variable- causes a change in dependent variable temperature (heat)
- dependent variable- color of the tea
- control factors- same type of tea, same amount of tea, same amount of baking soda, same amount of baking soda, same temperature, same amount of stirring time, same size test tube
- experimental errors- hole in tubing (won't see bottle fill with gas), stopper not snug (won't see bottle fill with gas), stirring rod may not be clean at the beginning
EXTRA QUESTION: There is less or equal condensation that forms at the top of the heated test tube because condensation comes from the baking soda and can't produce more than itself.
1.2 Volume Notes
- unit of measurement: cm³ (cubic centimeters)
- volume= l x w x h
- standard unit of length= meter (m)
- 100cm= 1m
- unit cube= a small cube (1 cm on each side)
Volume of liquids:
- use a graduated cylinder to measure volume *always check the intervals of scale*
- units= milliliters (mL) or cm³
- 1 mL= 1 cm³
- read from bottom of meniscus
Box Questions #1-13 pg. 8, 11-12
- Baking soda is used when baking because when it is heated, it releases a gas and that causes dough/ batter to rise.
- (don't answer)
- 50.0 cm³ of water are required to fill a graduated cylinder to the 50.0- mL mark.
- It is possible for box A (which has a greater volume than box B but, is has a shorter length than box B) because box A could have a longer height and width than box B.
- If you put a stone in a graduated cylinder containing 25.0 cm³ of water raises to 32.0 cm³ it means the stone is 7.0 cm³.
- a) It will take 8 cubes to build a cube that measures 2 cm along each edge.b) It will take 27 cubes to build a cube that measures 3 cm along each edge. c) volume for a= 8cm³ b=27cm³
- If one rectangle box is 30 cm long, 15 cm wide, and 10 cm deep it is still has a smaller volume than a rectangle that is 25 cm long, 16 cm wide, and 15 cm deep.
- The divisions on a cone- shaped graduated cylinder are not equally spaced because as the surface increases the height decreases.
- a) On the ruler I= 1.2 cm and II=3.8 cm b) on the other ruler III=1.66cm IV=2.51cm V=4.50cm c) You should report the positions of the arrows in part b to the nearest 0.01 cm and not to the nearest 0.1 cm because it is more accurate.
- Each division in the graduated cylinder equals a) 0.1 cm³ b) 0.2 cm³
- a= 4.0 cm³ b= 1.29 cm³ (see image on page 12)
- To round up to 12 cm the measurement could have been 11.5-12.4 cm.
To round up to 12.0 cm the measurement could have been 11.95-12.04 cm.
To round up to 12.00 cm the measurement could have been 11.955-12.004 cm.
13. The advantage to making a graduated cylinder narrow and tall rather than short and wide is that the meniscus won't dip as much and the less surface the more height which means the lines are further apart so it is easier to read.
1.3 Reading Scales
- check that pan is clean and dry
- always zero- balance the scale before EACH massing
BOX QUESTIONS #9-13 PG 11-12
- Be able to read a graduated cylinder and a ruler
- The advantage to making a graduated cylinder narrow and tall rather than short and wide is that it is easier to read because the lines are further apart.
POST LAB NOTES FOR THE DISPLACEMENT OF WATER LAB
- Why were lab groups instructed to use different amounts of sand?
To show it didn't matter what you started with, the amount of air space was approx. 40%
1.5 LIMITATIONS OF VOLUME AS A MEASURE OF MATTER/ 1.6 EQUAL ARM BALANCE
- beqa: an ancient standard mass unit used in egypt approx 7000 years ago. It was the standard unit
- There are two advantages to an electric balance- it takes only seconds to mass an object and it can subtract the mass of the container and give you the mass of the contents alone
1.8 THE SENSITIVITY OF A BALANCE
- Mass of penny before 1982- 95% copper 5% zinc
- After 1982- 2.5% copper 97.5% zinc
- 1943- mad of steel and zinc, copper was needed for bullets, a 1942 copper penny sold for 82,500 dollars
The sensitivity of a balance: the lightest mass that you can expect the balance to detect, add or subtract the margin of error when you mass something
Pg 24 and 25
30) know how to find the volume of a box
31) see textbook
34) When you pay for coal it is an advantage that you pay by mass because then you don't pay for air. When paying for liquids it is more practical to use volume.
If the height of the space was half the length of an edge of a unit cube, what was the volume of the box?
If the height of the space was 0.47 of the length of an edge of a unit cube, what was the volume of the box?
6.5x7.47= 224.1 cubic cm
2. What is the mass of an iron bar that is 2cmx4cmx11cm? (1 cm cubic of iron has a mass of 7.8g)
3. a volume of 87 cm3 of dry sand is added to 46 cm3of water for a total volume of 104 cm3.
Volume of dry sand
Volume of water
Volume of sand and water
Volume of sand alone
Volume of air space
% of dry sand that is sand
% of dry sand that is air space
What is the volume of water that fills the air spaces in the dry sand?
29 cm3 (volume of space)
What is the volume of the water that does not fill the air spaces in the sand?
water - air 46-29= 17 cm3
4. to stay physically fit, Mr. Leeds is constantly training (and injuring himself). He weighs a trim 178 lbs. What is his weight in kilograms?
178/2.2= 81 kilograms.
Part B: Lab Experiments:
1. During the Heating Baking Soda Experiment a lab group does not realize that they have a hole in their rubber tubing. How will this affect their understanding of the lab?
This would affect their understanding because they wouldn't know baking soda releases carbon dioxide.
2. During the Reaction in a Bag Experiment a lab group does not realize that there is a hole in their zip lock bag. How will this affect their understanding of the lab?
This will affect their their understanding because they won't know that substance A releases a gas and the bag will not inflate.
3. For the Measuring by Displacement of Water Experiment Mr. Leeds assigned lab groups different amounts of dry sand to begin the lab. Why?
So that we would notice that no matter what the amount the air space would take up the same percentage of the dry sand.
During the ice and water lab a lab group forgot to put the cap on their bottle. by the time they realized their mistake some condensation had already formed on the outside and inside of the bottle. They should:
start the lab over
In all four experiments from Chapter 2 the common theme involved investigating changes in mass of different states of matter. You now know that in all the labs there should be no change in mass because:
Law of conservation of mass
You are working in a class with no air conditioning, it is 90 degrees. Your lab is to take the mass of water (65 degrees) 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 the Mi and then freeze
A lab group dissolves 2g of salt into 8 cubic centimeters of water in a beaker with no cover. AFter a few days all of the water has evaporated. What will remain in their beaker?
2g of salt
The following data were recorded in an experiment involving heating copper and sulfur:
Test tube, rubber sheet, and rubber band 23.681 g
Test tube, rubber sheet, rubber band, copper, and sulfur before reaction 25.524 g
Test tube, rubber sheet, rubber band, and products after reaction 25.498 g
Mi of the substances
Mf of the substances
What is the percentage change in mass of the reacting substances (round to the tenths place)?
1.4 change (∆M/ Mi= x/100)
1. Describe a possible error (specific to the lab) discussed in class, which could lead to a loss in mass during the Mass of a Gas lab. Be sure to explain why this error would cause a loss in mass.
If there was a ring of water i the pan during Mi.
Explanation: It would cause a decrease because if it was on the bottom of the bottle it would evaporate and then would not be there for the Mf making the ∆M a decrease.
2. Describe a possible error (specific to the lab) discussed in class, which could lead to a loss in mass during the Mass of Copper and Sulfur lab. Be sure to explain why this error would cause a loss in mass.
Hole in rubber sheet or if the sheet not on tight.
Explanation: The gas escapes during the reaction.
3. During an experiment of Ice and Water a gain in mass is noted by a lab group. Give a possible error (specific to the lab), discussed in class, as to how this gain in mass could have occurred. Be sure to explain why this error would cause a gain in mass.
If there was condensation outside of the bottle.
Explanation: If there was condensation that formed in between massings and you didn't wipe it off it would add weight (mass) to the Mf.
Mass of solid, test tube, and water before reaction
Mf of the substances
202 cubic centimeters
Find the density of the gas:
3.9 g/ cubic centimeters x 10-3
The volume of gas generated by combing 1.5 g of sodium bicarbonate and 6.5 g of sulfuric acid is 380 cubic centimeters. After the reaction the remaining acid and solid have a mass of 7.2 g. What is the density of the gas produced?
2.1x10-3 grams per cubic centimeter
Estimate the mass of hydrogen in an empty room with the following measurements: 4x6x9 (density of hydrogen is 8.4x10-5)
If the rubber tubing is not in properly what will happen
the volume decreases density increases