IPS Exam
Sydney Aronberg
Safety
- Goggles- keep them over your eyes until Mr. Leeds says to put them away
- Fire extinguisher
- Fire blanket
- Eye wash/shower
For Every Lab-
- Report accidents to Mr. Leeds IMMEDIATELY
- Nurse extension: 2828
- Clean-up completely
Chemicals-
- Never taste chemicals
- Never waft solids
- Always waft liquids
- Do not touch chemicals
- Always wash you hands with soap and water after labs
- If chemicals touch your skin: flush skin with water for 1 minute and notify Mr. Leeds
Glass-
- Hot and cold glass look the same
- Never used chipped or broken glass
- Dispose broken glass in proper trash
- Never use force to remove or insert glass
Alcohol Burners-
- Roll up sleeves
- Put up long hair
- 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 if it is being heated
- Make sure burner is capped and flame is out when you are done
Reaction In A Bag Lab
endothermic reaction- cold is produced
Error-
- hole or rip in the bag: you wouldn't know a gas is being produced
Red Liquid= Phenol Red
used as a ph indicator
Solid A= calcium + chlorine
acidic, hydrotropic- absorbs water
Solid B= sodium bicarbonate
sodium bicarbonate- baking soda, alkaline
Heating Baking Soda Lab
Control Group- unheated test tube
Experimental Group- heated test tube
Indicator- tea
Independent variable- heat
Dependent variable- color of tea
Control factors- same type of tea, same amount of baking soda, same amount of tea
Experimental Error- hole in tubing, stopper isn't tight, not cleaning stirring rod
Volume
The unit of measurement is cm3. To find the volume you must multiply l x w x h. A standard unit of length is a Meter (M). 1 cm = 0.01 M and 100 cm = 1 M.
Volume of Liquids-
A graduated cylinder is used to measure the volume of a liquid. You must always check the intervals or scale of a graduated cylinder. The unit of measurement is milliliters (mL). You should always read volume from the bottom of the meniscus.
Using A Balance
- Make sure the pan is clean and dry
- "Zero Balance" by pushing riders to the left and using the adjustment knob
- *Never switch pans
- *Pick up balance by the red bar
Displacement of Water Lab
Experimental Errors- sand sticks to sides of wet cylinder, if you poured water into sand
Volume of Sand Alone- sand and water - water
Volume of Air Space- dry sand - sand alone
Fraction of Sand that is Air- air (over) dry sand
Mass
- Beqa- ancient standard mass used in Egypt
- earliest balance found in Egypt (about 7,000 years old)
- standard unit of mass- grams
- 1 kg = 1,000 grams
- 1 kg = 2.2 lbs
Sensitivity of a Balance Lab (Part 1)
In the first part of the lab, we mass a penny and stopper alternately 4 times. We realize that each time we have a slightly different mass for the penny. This is because we all read the balance differently.
To find the mass of a single square- mass of 20 x 20 square (over) 400*if the range (biggest-smallest) is larger than the sensitivity of a balance than some group made a mistake (applying to a group of data)
Sensitivity of a Balance Lab (Part 2)
Delta- triangle symbol, change
Delta M- change in mass
To find the Delta M- ending mass - initial mass of stopper
To find the sensitivity- Delta M (over) number of yes's
Sensitivity of a Balance Lab Notes
Pennies:
- Before 1982: 95% Copper, 5% Zinc
- After 1982: 2.5% Copper, 97.5% Zinc computer technology made the price of copper go up
- 1943: made of steel and zinc copper was needed for shell casings (bullets for WW II) a 1943 copper penny has sold for $82,500
Sensitivity of Balance:
- sensitivity- the lightest mass that you can expect the balance to detect
- (+,-) the margin of error when you mass something
The Mass of Dissolved Salt
We found the mass of salt and a bottle with water (the salt not mixed). Then we mixed the salt in the bottle to see if adding salt to the water created a decrease/increase/no change in mass.
Mf- Mass final
to find ∆M... Mf-Mi
Errors=
if you clean pan between Mi and Mf
outside of bottle is wet during Mi
if you shake bottle (spill, leak)
To get dissolved salt back: let water evaporate, there will be same amt. of salt
*if someone is between -.02 and .02, it is possible they got no change*
Histograms
interval- one full line to the next
*HISTOGRAM RULE*- if data falls on a line, graph in the column to the right
Ice Ice Baby Lab
During this lab we found the mass of ice in a bottle then we found the mass of water (the same ice melted) and we wanted to see if there was a increase/decrease/no change in mass.
Mf of Water- bot/cap/water - bot/cap
∆M- Mf-Mi
Condensation:
Where does it come from? warm water vapor in air touches cool surface of bottle
How does this affect the lab? it will add extra mass for the Mf
Errors=
not wiping of condensation
bottle is wet during Mi
shaking bottle may cause leak
Copper and Sulfur
when it cools- sulfur bonds with copper and forms sulfur sulphide
sulfur is hydrotropic
errors:
1. rubber sheet has a hole
2. sulfur ticks to sides of tube
3. clean pan b/w mi and mf
Percentage of Change-
∆M/Mi= x/100
The Mass of Gas
has... aspirin, citric acid, adn sodium bicarbonate
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
**all changes should be close to zero because of sens. of balance
Properties
Property of an object: does not tell you what it is made of
Property of a substance: helps identify what the object is made of
- Sharp- object
- Heavy- object
- Stainless-steel- substance
- Knife- object
- Small- object
- Chunk- object
- Black- object
- Tar- substance
- Beautifully carved- object
- Wooden- substance
- Chair- object
Mass and Volume
cylinder is wet during the mass (from volume)- add mass
if water splashes out of g. cyl.- less volume
1. objects that are made of the same substance that have the same volume will have the same mass
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
Density
aluminum: 2.7 g/cm3
brass: 8.5 g/cm3
The Density of a Solid
cube 2 is probably different.
Density of a Liquid
-not rinsing out grad. cyl. between substances
-dry grad. cyl. between masses
- not re-massing grad. cyl. for 1st mass
Epsom Salt=
-magnesium sulfate
Density of a Gas
-if you don't put the foil back for the Mf
- if you touch the tablet after Mi
- stopper isn't on tight