Science Study Guide Exam
from start of school to 12/12/13
CHAPTER 1 (lab safety)
-Googles and fire stuff
- don't touch or taste
-don't look down out hair up.
Reaction in a Bag
-phenol red (indicator that measures acidity, 0-14, 0-6 acid, 7 neutral, and 8-14 alkaline)
-below 7 yellow above 8 pink
-calcium chloride acidic
-hydrotropic- absorbs water (attracted to water)
uses- canned veggies, electrolyte in sports drinks, gives pickles salty flavors.
-turns the red liquid yellow
- Sodium bicarbonate (baking soda)
-uses- baking, toothpaste, laundry detergent.
-turns the red liquid pink
-If there was a whole in bag would not know there was gas
Where heat and cold come from and gas
Exothremic(heat) reaction- solid a with liquid
Endothermic(cold) reation- solid b with liquid
Gas- solid a and b with liquid.
Heating Baking Soda Lab
- at top of t. tube foggy, comes from hot gas touching the cooler test tube and turning back into a liquid.
-gas that leaves the test tube and into bottle comes from b soda.
-heated baking soda with tea was chunky and the tea darker and the unheated was lighter and still a powdery substance. They are not both baking soda because they turned different colors when tea was added.
Control Group- unheated test tube
Experimental Group- heated test tube
Indicator- The tea (showed that heated b soda is no longer b soda)
Variable is a category you try to measure.
-independent variable causes a change in the dependent variable- temperature (heat)
-Dependent Variable was the color of tea because it depended on heat.
- same type of tea
- same amount of b. soda
- same size t. tube
- same stirring time
-a hole in tubing (wont see gas fill bottle)
-stopper not snug (same as above)
-not clean stirring rod before stirring. (could contaminate the test tubes)
-Less/equal to because condensation comes from b. soda and it cannot produce more than itself (b. soda)
Box Questions 1, 3-13
See book for q's1. When baking soda is heated it allows dough/batter to rise(bread/cookies/muffins/etc.)
4. Box a's height and width are greater
6. 8, 27, 8cm3, 27 cm3
7. the second one
8. Because the cone gets wider as the numbers increase, as height increases numbers decrease
9-13 see lab book.
-standard unit of length 1 meter/cm
-1cm=0.01 m or 100cm = 1m
- use graduated cylinder
- always check scale/intervals
-read from bottom of meniscus
- alwAYS ZERO THE BALANCE BEFORE EACH MASSING
- push all riders to left and use adjustment knob
- never switch pans because each pan, holder, and weights are specific for each scale.
- pick up balance by red bar only
Measuring Volume By displacement of water lab
(v sand + water)-v of water= sand alone
v of dry sand-sand alone= air
air/dry sand=fraction of dry sand that is air and % of dry sand that is air
sand/dry sand= % of dry sand that is sand and fraction of dry sand that is sand
- sand sticks to sides of wet cylinders ( v of sand and water would be to low)
-pour water into sand (water sits on top of sand because the air spaces do not allow the water to filter down)
Why where groups instructed to use different amounts of sand? (what was the purpose?)
To show that it does not matter how much dry sand you began with, each group has approximately 40% air space.
Sensitivity of a Balance
mass of single square= m of 20x20/400
sensitivity of balance= AM/ number of yeses
SENSITIVITY OF A BALANCE
-the lightest mass the you can expect the balance to detect + or - the margin of error when you mass something
1.not drying off cap-water in mi thats is not there for mf.
2. spill salt
3. remove cap before mf
4.when pour into bottle spillage or leakage.
5. not shaking long enough- salt not dissolved
6. cap not on tight- spillage and leakage
MF-mi= Delta M
-put zero in middle (all intervals in middle)
-go by given intervals
-if number falls on line shade the box to the right.
2.4 (Ice ICe Baby)
Condensation on Bottle
-comes from warm water vapor in the air (humidity) when it touches cool surface of bottle it turns from gas to liquid.
1. not wiping off condensation (gain in mass)
2.bottle is wet during mi- loss of mass
3.shaking the bottle and losing liquid through cap- loss
Mass of cap and bottle (g)
Mass of bottle cap and ice (g)
Mi of Ice (g)
bottle, cap, ice - bottle cap
Mass of bottle cap and water (g)
Mf of water (g)
bottle, cap, water - bottle and cap
2.5 (Intepreting data)
mass of substances and t tube un heated- mass of t. tube= mi
mass of t tube unheated- mass of t tube heated with substances= mf
mf- mi= delta m
Yellow Smoke- water in sulfur turns to gas and rises in tesst tube becasue sulfur is hydrotropic and has water.
When it cools sulfur bonds with copper making copper sulfide
-ruber sheet has a whole in it (gas would escape)
- rubber sheet is not on tight (gas escapes)
- sulfur sticks to t tube (wont react)
- clean pan between mi and mf (for all balance labs)
2.6 the mass of a gas
bottle, cap, tablet, water (after reaction)(mf)-bottle, cap, tablet, water (mi)(before reaction) =delta m
mf- mass after gas is released=mass of the gas
-cap is not tight or cap not sealed quickly enough (gas will escape causing a decrease in mass)
-water in pan during mi (lose or gain i think in mass, water there in mi but not there in mf)
-cap is wet during mi (alka-celtzer starts to react making gas and loosing gas) (starts to dissolve) (loose in mass)
-touch tablet after mi loss in mass (tablet breaks in hand like britlle)