1st Study Guide

9/18/13

Lab Safety

  1. Always keep your goggles on until Mr. Leeds says to
  2. Nurse Ext: 2828
  3. Report all accidents to Mr. Leeds and use common sense
  4. Safety Equipment: Fire extinguisher, Fire Blanket, Eye Wash/Shower
  5. Never: Taste chemicals and waft solids/powders
  6. Always: Waft Liquids, Avoid Touching chemicals, Wash hands with soap and water, and flush skin with water for 1 minute (Then Tell Mr. Leeds
  7. Never used chipped glass or broken glass(tell Mr. Leeds if broken)
  8. Never use force; know hot glass and cold glass look the same
  9. Alcohol Burners: Roll up sleeves, pull up long hair, never walk away from a lighter, Never point the open end of a hot test tube at anyone, Do not look down into a beaker when it is being heated, and make sure the heater is capped and the flame is out when done
  10. You must clean-up!


Reaction in a Bag

  1. The purpose of this lab is too see what happens when you combine chemicals
  2. We learn that Calcium Chloride and a liquid creates heat, while Sodium Bicarbonate and a liquid creates coldness
  3. Calcium Chloride, Sodium Bicarbonate, and a liquid create gas
  4. A possible experimental error in this lab is that we would not know if there is a hole in the bag or not; a hole would be a problem because the gas created from the combination would escape and thus the bag would look different
  5. Calcium Chloride is used in things like canned vegetables because it is acidic
  6. The Sodium Bicarbonate is used in brushing teeth
  7. The Red Liquid used is Phenol Red (a ph indicator)


Heating Baking Soda

1. The purpose of this lab is to observe and record the reaction that occurs when baking soda is heated


2. Experimental Error- If there is a hole in the rubber tubing and if the stopper is not snug

3. We learn that the baking soda creates a gas, which then moves up in the test tube and turns into a liquid. It than droops down as a liquid and becomes hot again, turning it into a gas once more.

4. We learn many terms in this experiment

5. Control Group: Unheated test tube

6. Experimental Group: heated tube

7. Indicator- The tea because it showed that when the tea is heated the baking soda changes (as the color is different in the tea that is with heated baking soda than the one that isn't)

8. Independent Variable- The heat

9. Dependent Variable- Tea Color



Measurement Lab

Volume Notes:


1. The unit of measurement in volume is cubic centimeters

2. There are 100 centimeters in a meter

3. A meter is the standard unit of measurement

4. A unit cube is a cube with 1cm cubed on each side

5. Use a graduated cylinder to measure the volume of a liquid and always check the intervals being used

6. We measure volumes of liquid with milliliters and centimeters cubed, they are equal

7.Read from the bottom of the meniscus when measuring the volume of liquid.

Balance Notes:

1. Check that the pan is dry and clean

2. Zero balance the scale before measuring by pushing all the riders to 0 and by using the adjustment knob if need be.

3. Never switch pans because they are all meant for a certain scale

4. Pick up the balance by the red bar only, and don't zero balance the scale when done because this strains the scale.

1.4 Displacement of Sand

Error:


1. Sand sticks to sides of wet cylinder-lose sand

2. Pour water into sand-The water will sit on top of sand


Extra Questions: No matter how much dry sand you start with, each group gets about 40% of their sand as air space.

1.6 Mass

Beqa: Ancient standard mass used in Egypt


-Earliest balance found in Egypt (7,000 yrs old)

-Standard unit=Grams

-1 kg=2.2 lbs

1.8 (First usage of Sensitivity)

Change in mass divided by the number of yes's=sensitivity of the balance

The Penny


  1. Before 1982- 95% copper 5% zinc
  2. After 1982- 2.5% copper 97.5% zinc
  3. 1943- Made out of steel and zinc casings (bullets)

Sensitivity- The lightest mass that you can expect your balance to detect +- the margin of error when you mass something


2.1 (Mass of salt decreasing)

Error:


-Clean pan before Mi and Mf

-Outside of bottle is wet during Mi

-Not drying cap

-Removing Cap b4 MF-Spillage/Leakage

-Cap not on tightly

Random:

-Evaporate water to get the salt back

-6/11 groups could have no change in mass

2.4 (The Mass of Ice and Water)

Condensation forms: Hot vapor touches the cool surface



Errors:

-Not wiping off the condensation-gains mass

-Bottle is wet during Mi

-Shaking bottle may lead to water leaking out

2.5 Mass of Copper and Sulfur

Yellow Smoke- Water in sulfur turns to vapor (gas) and rises in the test tube


When it cools- the sulfur bonds with copper and forms copper sulphide


Experimental Errors:

-Rubber sheet has holes-escape

-Rubber sheet isn't tight on test tube-escape

-Sulfur sticks to the sides of the test tube

-Clean pan b/w Mi and Mf

2.6

-Does the mass change when a solid and liquid produce a gas?


-Difference between mass before gas is realized and after gas is released =mass of the gas


Errors:

Cap is not tight or not put on quick enough-Gas escapes

Water in pan during Mi-lose mass

Cap is wet during Mi-Lose mass

Picking tablet up after Mi-Lose mass


Alka-Seltzer: Antacid and pain relief

-Aspirin

-Citric Acid

-Sodium Bicarbonate-Produces gas

Conservation of Mass

  1. Closed System: A space where nothing can leave or enter
  2. In a closed system mass will remain constant regardless of the processes inside the closed system


3.1 (Characteristic Property)

  1. Property of an object: Does not tell you what it is made out of
  2. Property of a substance: This helps you to identify what the object is made out of
  3. Vocab is in the class notes folder

3.2 (Mass and Volume)

  1. Stuff of the same substance (of the same density) will have the same mass
  2. In order to maintain a specific density, if the volume goes up the mass must go up accordingly, or vice versa
  3. Aluminum- 2.7g
  4. Brass- 8.5g
  5. Remember the graphs
  6. Shape does not matter in density (Long aluminum cylinder and short aluminum cylinder had the same density)


3.5 (Density of a Solid)

  1. The histogram shows that Cube 1 and the Slab are most likely the same substance. Cube 2 is obviously a different substance.

The Rock:

  • Sedimentary
  • Everyone gets different densities because it is made from different substances (sediments)
  • The rock is formed by many substances being compressed together


3.6 (Density of a Liquid)

Magnesium Sulfate=Epsom Salt


1. Consumed as a laxative

Solid A-lots of Epsom Salt

Solid B-Less Epsom Salt


Errors:

Not rinsing out the graduated cylinder between substances

Not re-massing the graduated cylinder

3.7 (Density of a Gas)

This is hard to measure because you can't see or contain it


Errors:

  1. Not putting foil back for mf-Density is bigger
  2. Touching tablet after Mi-Mass to big
  3. Stopper not on tight