Science Study Guide Exam

from start of school to 12/12/13

CHAPTER 1 (lab safety)

-equipment

-Googles and fire stuff

-Chemicals

- don't touch or taste

-burners

-don't look down out hair up.

Reaction in a Bag

- observed what happened when multiple chemicals were mixed.

RED LIQUID

-phenol red (indicator that measures acidity, 0-14, 0-6 acid, 7 neutral, and 8-14 alkaline)

-below 7 yellow above 8 pink

Solid A

-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

Solid B

- Sodium bicarbonate (baking soda)

-not acidic

-uses- baking, toothpaste, laundry detergent.

-turns the red liquid pink

Experimental error

-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

-observed what happened when heating baking soda

- 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.

CONTROL FACTORS

- same type of tea

- same amount of b. soda

- same size t. tube

- same stirring time

Experimental errors

-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)

Extra Q

-Less/equal to because condensation comes from b. soda and it cannot produce more than itself (b. soda)






Lab 1.1 Heating Baking Soda

Box Questions 1, 3-13

See book for q's

1. When baking soda is heated it allows dough/batter to rise(bread/cookies/muffins/etc.)

3. 50cm3

4. Box a's height and width are greater

5. 7cm3

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.

Volume Notes

-cm3

-volume= lxwxh

-standard unit of length 1 meter/cm

-1cm=0.01 m or 100cm = 1m


Liquids

- use graduated cylinder

- always check scale/intervals

-ml=cm3

-read from bottom of meniscus

Balace Notes

- check that balance is clear and dry


- 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

Calculations


(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

EXPERIMENTAL ERRORS

- 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)

EXTRA Q

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

Calculations


mass of single square= m of 20x20/400

sensitivity of balance= AM/ number of yeses

AM= mf-mi

SENSITIVITY OF A BALANCE

-the lightest mass the you can expect the balance to detect + or - the margin of error when you mass something

CHAPTER 2

2.1

- see if the mass of salt decreases when salt dissolves in water.


Experimetnal Erros-

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


2.2 (Histos)

- put zero on line (all intervals on line)

-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)

- to determine if the mass of ice will increase, decrease, or stay the same when melted.


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.

Experimental Errors

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

Data Equations



Mass of cap and bottle (g)

normal mass



Mass of bottle cap and ice (g)

normal mass



Mi of Ice (g)

bottle, cap, ice - bottle cap



Mass of bottle cap and water (g)

normal mass



Mf of water (g)

bottle, cap, water - bottle and cap



ΔM (g)

mf-mi



2.5 (Intepreting data)

Calculations


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

Experimental Errors

-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

Calculations

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

Errors

-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)

Alka-seltzer