Intro. to Physical Science

Exam

Zack Shevin

Pine Crest School


Lab Safety Notes

For every lab


Goggles must be kept OVER YOUR EYES until Mr. Leeds says to put the away

Even if you are already finished and cleaned up

Report all accidents/spills to Mr. Leeds immediately

Try your best to use common sense


In case of Emergency

Nurse: ext: 2828


Safety equipment in classroom

Fire extinguisher

Fire blanket

Eye wash/shower


Chemical

Never taste chemicals

Always WAFT liquids to detect odor

NEVER WAFT SOLIDS/ 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


Glass

Hot 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


Alcohol Burners

Roll up sleeves, put UP long hair, NOT just pul back

Never walk away from a lit burner

Never point the open end of a hot test tube what yourself or someone else

Do not look down into a test tube while its being heated

Make sure burner is capped and flame is out when done


End of Experiment

CLEAN UP AREA AND MATERIALS COMPLETELY! (or you lose points)

Make certain that burner is out if one was used

Keep goggles on until Mr. Leeds says to put them away

1.1-1.3

Reaction in a Bag Post-Lab

Red Liquid


Phenol Red


  • used a pH indicator
  • Below 7 turns yellow
  • Above 7 turns pink


pH Scale

  • Measures acidity
  • Goes from 0-14
  • 0-7-14
  • acid- neutral- alkaline
  • Lemon juice 1.5
  • Tums 10



2 Solids

1. Calcium Chloride (A)


  • acidic
  • hydrotropic: attracted to water
  • uses: canned veggies, electrolyte in sports drinks
  • Flavors pickles

2. Sodium bicarbonate (Baking Soda) (B)



  • non acidic
  • uses: baking, laundry detergent
  • Toothpaste



EXPERIMENTAL ERRORS:


  1. Hole in the bag: you would not know that a gas was produced



CHEMICAL REACTIONS:

A and Liquid = hot

B and liquid =cold

A + B + LIQUID = gas

Scholar Reaction In The Bag Inquiry Demonstration and Lab Activity

Heating Baking soda post lab

Condensation comes from hot gas touching cooler top of test tube. Turns back to liquid



Different substances because they look different. Something in tube 1 is not tea or baking soda.


Control group: Unheated Test Tube

Experimental group: Heated test tube

Indicator: Tea (shows solids are different)

Variable: Something you try to measure

Independent: causes change in dependent (Temperature)

Dependent: changes based on independent variable (tea color)


Control factors:

Same type of tea

Same amount of b soda

Same amount of tea

Same stirring time

Same size of test tube


Experimental Errors:


  1. Hole in tubing releases gas so bottle would not empty
  2. If stopper not snug, bottle won't empty
  3. Stirring rod not cleaned before lab, could contaminate



Extra Q

The condensation was less than the baking soda because the Baking soda made the condensation


Box Question 1:

The gas produced by baking soda makes batter rise

Lab 1.1 Heating Baking Soda

Volume Notes 1.2

THE AMOUNT OF SPACE SOMETHING TAKES UP



  • unit of meaurement = cm cubed
  • volume= l x w x h
  • Standard unit of length meter
  • 1 cm = 0.01 m
  • unit cube- 1cm X 1cm X 1cm


Volume of Liquids

use graduated cylinder


ALWAYS check the intervals or scale

units- milliliters (mL) or cm cubed

Read from bottom of meniscus

Reading Scales

Metric system

Single Pan Balance

  1. check that pan is clean and dry
  2. "zero" balance before using
  3. NEVER switch pans

1.4 - 1.8

1.4 Sand

Method used in lab- the displacement of water method


Experimental Errors


  1. Sand sticks to sides of wet cylinder the measurement would be off
  2. Pour water into sand (water sits on top of the sand because the air spaces do not allow the water to filter down


Extra question

  1. Why different amounts of sand for different groups

To prove that no matter how much sand you started with, the amount of air space in the sand was approximately 40%



Calculations

Volume of dry sand mixed with water - volume of water = volume of sand alone

volume of dry sand - volume of sand alone = volume of air space

volume of air / volume of dry sand = fraction of sand that is air

Note: when finding the volume of a powder like sugar that dissolves in water, use another liquid. With sugar you can use the displacement of vinegar method to find the volume.


Note: to find the volume of something with air space that floats like a cork, use another object to sink the cork down. The formula would then be the volume of the weight, water, and cork - the volume of the water- the volume of the weight = the volume of the cork.


1.5 Limitations of Volume as a Measure of matter

When measuring volume of a solid by displacement of water we make an assumption that the volumes of the solid alone and the water alone add up to the volume of the solid and water together after mixed. This may or may not be correct, depending on the kind of solid. It is not correct of solids like rock salt.

1.6 Mass

Equal Arm- Balance

  1. Developed in ancient Egypt
  2. Egyptians used rocks with units of beqa


Mass- standard unit is grams (g)

1 kilogram (kg) = 1000 grams (g)

1 kg= 2.2 lbs


Three types of balances-


  1. equal arm
  2. single pan
  3. electronic

1.7

Single Pan vs. Electronic vs. Equal Arm


Electronic is the quickest

Single Pan uses riders

Large objects cannot be measured easily on an Equal Arm

1.8 Sensitivity of a Balance

Sensitivity of single pan balance- 0.1


Experimental Errors-

1. Graphite on squares would make mass greater and mess up measurements

2. Cutting groups unevenly would throw measurements off


End Mass - initial mass = ∆M

∆M divided by # of yes on chart = the sensitivity of the balance

Change in Mass/ # of yes= sensitivity of the balance


Sensitivity of balance= the lightest mass you can expect the balance to detect

or the margin of error when massing something

Penny

  • prior to 1982 penny 95% copper and 5% zinc


  • after 1982 penny 2.5% copper and 97.5% zinc


1943: penny made of steel + zinc


  • copper was needed in war to make shell casings for bullets


  • a 1943 copper penny has been sold for $82,500

Chapter 2

2.1 Mass of Dissolved Salt

Exp errors:


1. Not drying off cap

2. Removing cap before Mf

3. Cap not on tight

4. Spill salt when pouring into bottle

ALL RESULT IN DECREASES IN MASS!


If you have 2g of salt and dissolve it into a liquid, how would you get the salt back and how much salt could come back?

Letting the water evaporate would leave behind all 2g of the salt (we know this because it does not rain salt water)

Histograms (HEEEEESTOGRAMS)

Graph


Zero either on a line or in a space

Falls on a line ---> graph in box to the right of line

2.4 Ice Ice Baby Lab

Exp Errors:

Not wiping off condensation ---> gain in mass

Hand wet/ bottle wet during Mi ---> Lose mass

Shaking bottle ----> Some spills ----> Lose mass


Post Lab

CONDENSATION: forms when warm water vapor in the air (humidity) touches the cool surface of the test tube and becomes a liquid (was a gas before)


Condensation can form on outside or inside if there is no lid (only outside if sealed)

Restart lab if condensation forms on the inside


2.5- The Mass of Copper and Sulfur

Post Lab:


Melting point of copper :1100 C

Melting Point of sulfur: 112 C

Yellow smoke ---> the water in the sulfur becomes a vapor and rises

when it cools-----> sulfur bonds with copper and forms copper sulphide


Errors:

1. Hole in sheet / sheet pops off / not sealed around top of tube

Gas escapes, Mf too low

2. Sulfur stick to inside of test tube- does not react to heat (no real effect)

Lab 2.5: The Mass of Copper and Sulfur

2.6 Mass of a Gas

Exp errors:

1. Water in pan during Mi --> Lose mass

2. Cap not on tight enough or quick enough ---> gas escapes --> lose mass


Alka-seltzer: antacid and pain reliever

contains aspirin, citric acid, and sodium bicarbonate (baking soda)

the baking soda produces the gas


2.7 Conservation of Mass

  • Closed System - a space where nothing can enter or exit
  • Groups could have had not ∆M because of the sensitivity of the balance
  • All changes made in a closed system will not affect the mass
  • called- THE LAW OF CONSERVATION OF MASS


2.8 LAWS OF NATURE


BQ 17: A student wished to add a new experiment. The mass of a beaker of water was 109.44g, after heating the beaker the mass was 109.08g . Does this contradict the law of conservation of mass?

NO because a beaker is an open container which allows the water to evaporate. It is not a closed system.


BQ 19: Why does "what goes up must come down" express a law of nature?

Yes, it explains the law of gravity. It is a law of nature that only applies to earth.

BQ 20: is "on a sunny day the sky is blue" a law of nature?

Yes because if the sky was looked at on a sunny day it would be blue. This only applies to earth because of the atmosphere


Chapter 3

3.1 Characteristic Properties

Property of an Object: does not tell you what it is made out of.


Property of a Substance: helps you identify what the object is made out of.


example:

Sharp, heavy, shiny, stainless-steel knife

Sharp: Object

Heavy: Object

Shiny: Object

Stainless-steel: Substance

Knife: Object

3.2 Mass and Volume

Post Lab:

error: Cylinder wet during mass---> mass rises


Notes:

1. object that are made of the same substance that have the same volume, will have the same mass (regardless of their shape_

2. the mass of an object will double if its volume doubles

3. object that have the same volume but are made of different substances will not have the same mass (brass denser than aluminum)

3.3 Density

Density: D= m/v


unit: g/cm3 (grams per cubic centimeter)

Density does not change with mass or volume and depends only on the substance

know graphs like ones to the right

3.5 The Density of a Solid

Post Lab:


Can you tell which cube is denser just by holding?

Yes, same size, different weight


Can you tell whether the slab is denser just by holding?

No because you do not know the dimensions


CUBE 1 and SLAB SAME SUBSTANCE!

cube 2 different substance


The Rock

came from a bigger, sedimentary rock

Different densities because sedimentary rocks made up of different substances.


errors:

1. water splash- loss in volume and gain in density

2. Pain chipped off- loss in mass and loss in density

3. Measure same side of slab twice- change in volume

4. Find volume before mass of rock- the rock is wet during massing and mass increases causing density to also increase


3.6 Density of a Liquid

Pot Lab:


Errors:

1. Not remising empty cylinder

2. Outside of empty cylinder wet

3. Not rinsing out cylinder


Liquid B: Water

Liquid A: Water with Magnesium Sulfate

Magnesium Sulfate- sold under brand name epsom salt

3.7 The Density of a Gas

errors:


1. Foil not on Mf--> Mf Less---> Mass of a Gas more--->Density rises

2. Touching tablet after Mi--->Mass of Gas rises--->Density rises

3. Air bubble--> too much gas---> Volume rises---> Density falls

Gas Density should have been 1.8 X 10 to the power of -3 (because the tablet of alka-seltzer produces CARBON DIOXIDE

Density of a Gas.WMV

3.8

Be able to do equations involving density, mass, and volume.