Reaction in a Bag
- Phenol Red
- Used as a ph indicator
- Below 7 turns yellow
- Above 8 turns pink
- Measures acidity
- Goes from 0-14
- 0-7 acid
- 7- neutral
- 7-14 alkaline
Heating B. Soda
- Condensation comes from touching cooler surface at top of test tube cools back to a liquid
- gas comes from heated baking soda
Control Group- Unheated t. tube
Experimental Group- Heated t. tube
Indicator- Tea ( showed that heated t. tube wasn't b.soda)
Variable- Something you want to measure
Independent Variable- Causes a change in dependent variable -Temp (heat)
Dependent Variable- Color of tea
Control Factors- Same type of tea, same amt. of b.soda, same amt. of tea, same stirring time, same size t. tube
Exp Errors- Hole in tubing- bottle won't fill, don't clean stirring rod--> contaminated
Volume- LxWxH (AxBxC)
Standard unit of length- meter (m)
1 Centimeter (1cm)= .01 m
100 cm = 1m
A small cube 1 cm on each edge (1cm3)
Volume of Liquids
- Use a graduated cylinder to measure volume
- always check the intervals or scale
- units- milliliters (mL) or cm3
- 1 mL== 1cm3
- Read from bottom of meniscus
Single Pan Balance
- Check that pan is clean and dry
- Always zero balance before each massing
- push all riders to zero (left)
- Use adjustment knob if needed
- Never switch pans
- pick up balance by red bar only
- dont zero balance when done
- earliest one found in Egypt (approx. 7,000 yrs old)
Standard unit for mass: grams (g)
1kg= 1,000 g
1kg= 2.2 lbs
Sensitivity of Balance
- Means the margin of error when you mass something
Used for financial
If data falls on a line it is graphed in column to the right
Find largest and smallest number you must graph when you draw a histogram
Condensation of Bottle
Copper and Sulfur
Melting point of Sulfur- 112˚C (235˚F)
Yellow Smoke- water in sulfur turns to vapor (gas) and rises in test tube
When it cools- sulfur bonds with copper and forms copper sulphide
Citric acid (small) (flavor?)
Sodium Bicarbonate (produces gas)
Conservation of Mass
Law of Conservation of Mass
Mass will remain the same if its in a closed system.
Property of a substance- this helps you to identify what the object is made out of.
Mass and Volume
Ex: Long Aluminum Cylinder and the small 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: Brass and aluminum cylinders
2) is specific to liquids, solids, and gases
3) can help to identify substances
- All have different densities because rock is formed by many substances being compressed together. Different substances equal different densities.
- Goggles must be kept over your eyes until Mr. Leeds says ot put them away even if you are already finished cleaning up
- Report all accidents/spills to Mr. Leeds immediately
- Try your best to use common sense
- Nurse: ext: 2828
- Fire extinguisher
- Fire blanket
- Eye was/shower
- Never taste chemicals even if they look yummy!
- Always waft liquids to detect odor
- Never waft solids or 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 the 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 wile it is being heated
- Make sure burner is capped and flame is out when done
- Clean up area and materials completely or you will 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
Shell casings- Bullets
Meniscus- The curve point of where the water in a graduated cylinder falls. Read at the bottom for volume determination
Variable- Something you want to measure
Independent Variable- Causes a change in dependent variable
Sensitivity of a Balance- The lightest mass you can expect the balance to detect
Closed System- A space where nothing can enter or leave
Hydrotropic- Attracted to water
Density- Characteristic property, helps identify substances, specific to liquids, solids, and gases.
Interval- One line to the next.
Exothermic- Give off heat
Endothermic- Give off cold
Red Liquid- Phenol Red
pH Scale- measures acidity
cubic centimeters- unit of measure for volume
Volume- amount of space something occupies
cm- unit of measurement for length
Other things to know that aren't on here
Histograms and Graphs
Quesiton 5 part A
Chapter 2 Test
Part 1 Errors1) If in the Mass of Gas lab, the cap is not on tightly what would the outcome be?
Lose Mass, gas escape
2) In the Mass of Copper and Sulfur lab if there is a hole in the rubber sheet what would the outcome be?
Lose Mass, gas escape
3) In the Mass of Ice and Water lab if you don't wipe off the condensation on the bottle with water and ice what is the outcome?
Gain Mass, during Mf.
Part 2 Analysis
1) During Mass of Ice lab a group forgot to wipe condensation off bottle what should they do?
2) In all 4 experiments from Ch.2 in all the labs there should be no change in mass because?
Newton's laws of motion
all the labs followed einstein's theory
in all 4 labs everyone in class calculated no change in mass
Law of conservation of mass
3) If you were to place a bottle with water in it into a freezer, the liquid would solidify, what is a possible error you should be aware of?
All of the above
Condensation may form on the outside of the bottle
Condensation may form on the inside of the bottle during the Mi and then freeze
The water could start boiling and push the cap off
Part C: Calculation
1) What is the percentage change in mass of the reacting substances? (round to tenths)
∆M divided by Mi= % over 100..... -0.026 divided by 1.843 equals x over 100= -1.4%
D= m divided by v.... 21.4=800 divided by v, v= 37.4cubic centimeters
∆M is the mass of gas
∆V is the volume of gas
1) In order to calculate denisty we found both the mass and volume of the liquid in the graduated cylinder because it is the most accurate method and we did not have to transfer liquid.
2) During the density of gas lab the rubber tubing is incorrectly inserted near the bottom of the bottle, this will cause less gas to collect in the bottle.
3)If the error in the one above is made it will have the following affect: volume decrease, density increase.
4) when calculating the density of a rock it would be an error to find the volume prior to massing.
5) WHen the alka seltzer tablet is mixed with water, sodium bicarbonate within the tablet releases carbon dioxide.
6) In the density of a gas lab a student forgets to include the foil for the mf, the result is the mass of gas increases, density increases.
7) Epsm salt is the marketing name for Magnesium Sulphate.
- If the height of the space was half the length of an edge of a unit cube, what was the volume of the box?
LxWxH= V..... 6x5x7.5.... V= 225cubic centimeters
2) What is the mass of an iron bar that is 2cm x 4cm x 11cm? (1cubic centimeter of iron has a mass of 7.8g)
2x4x11x7.8..... 88x7.8= 686.49 cubic centimeters
3) A volume 87 cubic centimeters of dry sand is added to 46 cubic centimeters of water of r a total volume of 104 cubic centimeters. (round to whole number, convert fractions to percentages)
V. of dry sand- 87 cubic centimeters
V. of water- 46 cubic centimeters
V. of sand and water- 104 cubic centimeters
V. of sand alone- 58 cubic centimeters
V. of Air space- 29 cubic centimeters
% of dry sand that is air- 67%
% of dry sand that is air space 33%
58 divided by 87 = x over 100= 67%
41 divided by 87= x over 100= 47%
a) What is the volume of water that fills the air spaces in the dry sand?
87-58= 29 cubic centimeters
b) What is the volume of the water that does not fill the air spaces in the sand?
46-29= 17 cubic centimeters
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? (round to whole number)
178 divided by 2.2= 81kg
5) Use the following data to find the sensitivity of the balance used: (round to hundredths)
14.39-14.30= 0.09..... 0.09 divided by 6= 0.015 which equals 0.02g
6) FIve ips scholars use the same single pan balance to mass their friend's ring. None knew the results of the others. THeir results are listed in the table below:
a) Did any students make a mistake in their massing?
Yes their range is 0.045 which is much bigger than the sensitivity of the balance. (0.01-0.02)
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?
They wouldn't know a gas was being produced!
Part C: Measurment
1) Identify each mass, volume or other means.
3 cups flour- vol
1 tablespoon baking powder- vol
11 pound can of pumpkin- mass
1/2 teaspoon vanilla- vol
Cinnamon to taste- other
1/2 cup milk- vol
2) Identify volume, mass, or count
Water tank- vol
3) What would happen if Mr. Leeds gave you a range very small for 10 groups of squares?
You would be adding a lot of squares