Page 12- Physical Property - A property that can be observed with the senses, without altering or destroying the object Observed by taste, sight, sound, touch, smell The substance is not chemically changed to a new substance when you observe a physical property
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Page 12- Physical Property - A property that can be observed with the senses, without altering or destroying the object
Page 12- Physical Property - A property that can be observed with the senses, without altering or destroying the object. Observed by taste, sight, sound, touch, smell The substance is not chemically changed to a new substance when you observe a physical property. Physical Properties. Color - PowerPoint PPT Presentation
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Page 12- Physical Property- A property that can be observed with the senses, without altering or destroying the object
Observed by taste, sight, sound, touch, smell
The substance is not chemically changed to a new substance when you observe a physical property
PHYSICAL PROPERTIES Color
Luster – shiny, dull Odor – describes the smell State of Matter – solid, liquid, gas
aka: Phase of Matter Texture – rough, smooth
Mass – describes how much material is in an objectTool: triple-beam balance
Volume – describes how much space the object takes upTools: ruler or graduated cylinder (water displacement)
Density – describes how much mass is in the objects’ volumeFormula: Density = mass ÷ volume
1. What do vinegar, lemons, and green apples have in common?
2. What do soaps, shampoo, and detergents have in common?
1. Vinegar, lemons, and green apples have a sour taste and they are acidic
2. You may have accidentally tasted soapy water, shampoo, or detergents and noted that all of these cleaning agents have a bitter taste and are basic.
BELLWORK: THURSDAY
3/15/12 IT…
Ion– an atom that carries a charge because it has lost or gained an electronAtom with more electrons than protons – the atom becomes more negatively charged
An atom with more protons than electrons – the atom becomes more positively charged
The more electrons an atom gains or loses, the more negative or positive it becomes.
ACIDS & BASES- PAGE 15
Cation- “Paws”itively charged ion; lost electrons
The letter t in cation looks like a positive plus sign +: ca+ionEx: Hydrogen (H) can be a cation because it easily loses its one valence electron to become H+
Ex. Element X as a cation: X+
Anion- A Negative ION; gained electronsEx: Chlorine (Cl) can be an anion because it easily gains an electron to become stable as Cl-
Ex. Element X as an anion: X-
A substance which when added to water produces hydrogen ions [H+]The strength of an acid is based on the concentration of H+ ions in the solution. The more H+ the stronger the acid.
Characteristics of Acids:Taste sourReact strongly with metals (Zn + HCl)Strong acids are dangerous and can burn your skin
Examples of Acids:Vinegar Stomach Acid (Hydrochloric Acid- HCl) Citrus Fruits
ACID
A substance which when added to water produces hydroxide ions [OH -]The greater the concentration of Hydroxide ions [OH -] the stronger the base. Ex. NaOH (Sodium Hydroxide-a strong base) in water
Basic solutions are called alkalineCharacteristics of Bases:
Taste bitterFeel slipperyStrong bases are very dangerous and can burn your skin
Examples: lye (Sodium Hydroxide- NaOH)Ammonia
BASE
When acids and bases are combined, a process called neutralization occurs
The acids and bases chemically react to create water (a neutrally charged substance) and a salt
WHAT DO YOU THINK HAPPENS WHEN YOU ADD AN ACID TO A BASE?
+
HCl + NaOH H2O + NaCl
pH Scale- “Potential for Hydrogen” Scale; measures acids and bases 0 = pure acid 7 = neutral substance 14 = pure base
Litmus paper- indicator paper that changes colors to tell whether a substance is an acid or a base Acids - turn the paper a shade of red/orange Bases - turn the paper a shade of blue/green
HOW CAN YOU TELL THE
DIFFERENCE BETWEEN AN ACID
AND A BASE?
Bases are materials with a lesser concentration of H+ ions, and a greater concentration of OH - ions
They are measured from 7.1-14 on the pH scale
ACIDS VS. BASES (PH SCALE)
Acids are materials that have a higher concentration of H+ ions
Do your best from what you know, and use the periodic table and process of elimination to figure out the rest!
Due when you turn in your PACKET 9 next TUESDAY! (3/20)
1. What is the charge of an electron?
2. If an atom gains an electron, what happens to the charge of that atom?
What is it called? Write Chlorine (Cl)
after gaining an e’3. If an atom loses an
electron, what happens to the charge of that atom?
What is it called? Write Sodium (Na)
after losing an e’4. What would you call a
substance with the same amount of H+ and OH- ions?
1. Negative2. More negative charge-
makes the atom negative Negative Ion = Anion Cl-
3. Lose negative charge- makes the atom positive
Positive Ion = Cation Na+
4. Neutral!
BELLWORK: FRIDAY 3/16/2012
1. Why is it important to keep your goggles and lab apron on at all times?
2. Why is it important to use lots and lots of water if you accidentally spill an acid or a base on your skin/in your eyes?
1. They will protect from any chemicals splashing up into your eyes or on your body.
2. Water is usually neutral (pH 7). Adding lots of water to the acid or base will neutralize any of the corrosive material that has gotten on your skin, and will dilute the strength of the acid or base so that it will not burn or irritate you.
ACIDS & BASES LAB
Goals/Objectives Steps through Lab NOW: Make
Predictions on Data Table
Completing the data collection chart
Conclusion Questions Extension Questions
Work in pairs 14 stations
NaOH and HCl with Mrs. Cole
1 ½ minutes at each station
Stay at your station Take tray with you to
each station Only 1 drop/substance Record pH values of
the substances Time’s up? Move
quickly and quietly to the next station
Stay on chair-less side of table
Change aprons at halfway point
ACIDS AND BASES LAB- PAGE 16
1. Why do you think you were asked to include HCl and NaOH in a test of household products?
2. Lemons and oranges have nearly the same acidity and pH. Why might it be easier to eat an orange than a lemon?
3. What did you notice about the pH of distilled (purified) water vs. tap (sink) water? Why is there a difference?
4. Why do you suppose that most body fluids (i.e. saliva, blood, tears) have a pH that is neutral/almost neutral?
ACIDS AND BASES CONCLUSION QUESTIONS
Take home 1 strip of litmus paper and, paying close attention to the safety warnings on each substance, test the pH of liquid substances in your cupboards and cabinets. Fill in the chart and tape or glue your litmus strips in the appropriate column, when they are dry. Tear the strip into 6 pieces Do tests for 6 items
ACC ONLY: Design an experiment similar to the
one completed in class to determine the pH values for solid household substances, such as: antacid tablets, uncoated aspirin tablets, salt, sugar, dishwashing detergent, etc. Write the procedure for how you would conduct this experiment.