chemical vs physical properties

21
Chemical vs physical properties

Upload: keely-robles

Post on 02-Jan-2016

100 views

Category:

Documents


3 download

DESCRIPTION

Chemical vs physical properties. Elements and compounds can be described by their chemical and physical properties. Physical property : characteristic of a substance you can observe (using your senses) without changing it into something else State of matter (solid, liquid, gas) - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: Chemical vs physical properties

Chemical vs physical properties

Page 2: Chemical vs physical properties

Elements and compounds can be described by their chemical and physical properties

Physical property: characteristic of a substance you can observe (using your senses) without changing it into something else

• State of matter (solid, liquid, gas)• Melting, freezing, boiling point• Magnetism• Density• Color• Shape• Malleability• Solubility• Specific heat

Page 3: Chemical vs physical properties

Chemical properties: properties of an element or compound in a chemical reaction

• pH• Reactivity• Flammability/Combustion• Rusting• Bond

Page 4: Chemical vs physical properties

Practice on Identifying Chemical and Physical Properties1. Water boils at 100 degrees Celsius. 2. Diamonds are capable of cutting glass. 3. Water can be separated by electrolysis into hydrogen and

oxygen. 4. Sugar is capable of dissolving in water. 5. Vinegar will react with baking soda. 6. Yeast acts on sugar to form carbon dioxide and ethanol. 7. Wood is flammable. 8. Aluminum has a low density. 9. Ammonia is a gas at room temperature. 10.Bromine has a red color.

Page 5: Chemical vs physical properties

Which of the following conclusions can be drawn from the information shown?

a. Most types of matter heat up at the same rateb. Most types of matter cool at the same ratec. It takes less energy to heat 1g of silver than 1g of goldd. It takes more energy to heat 1g of water than 1g of copper

Material Specific Heat

Aluminum 0.899

Copper 0.387

Gold 0.129

Silver 0.234

Water 4.182

Wood 0.176

Page 6: Chemical vs physical properties

Magnesium melts at 650°C. If a 100g sample of magnesium melts at 650°C, then a 75g sample would melt at:

a) 325°Cb) 650°Cc) 487.5°Cd) 162.5°C

Page 7: Chemical vs physical properties

Chemical change: atoms are rearranged, I have different substances at the end of a chemical reaction/change

• Change in color• Formation of precipitate (L+LS)• Formation of a gas• Creation of light• Burning• Change in temperature (exothermic,

endothermic)

Page 8: Chemical vs physical properties

Changes can be physical or chemical

Physical changes do not rearrange atoms, I have the same substance I started with. I can reverse a physical change

Change in shapeChange in phaseDissolving

Reversable

Page 9: Chemical vs physical properties

Practice on Identifying Chemical and Physical Changes

1.Dry ice, solid carbon dioxide, is sublimed at room temperature.

2.Salt is dissolved in water. 3. Iron rusts in a damp environment. 4.Gasoline burns in the presence of oxygen. 5.Hydrogen peroxide decomposes to water and

oxygen.

Page 10: Chemical vs physical properties

Combustion: reacting with oxygenfrequently producting CO2& water

C3OH + O2 CO2 + H2O + heat

2Mg + O2 2MgO + Heat

______________________________________2H2 + O2 2H2O + heat

NH4 + NO2 N2O + H2O

Page 11: Chemical vs physical properties

Compounds or molecules are represented using a chemical formula

4CO₂Subscripts (little number) tell you the

number of atoms in the 1 molecule of the compound

Coefficients (big number out front) tell you how many molecules

(no number means the number is 1!)

Page 12: Chemical vs physical properties

Calculate the number of atoms of each element

AgMnO4

AlBO2

CH3OH

BaSi2O5

Page 13: Chemical vs physical properties

Calculate the total number of atoms of each element

2AgMnO4

6AlBO2

7CH3OH

2BaSi2O5

KNO3

Page 14: Chemical vs physical properties

Conservation of Mass

Mass on the reactant side of the equation equals the mass on the product side of the equation

Number and type of atoms on the reactant side of the equation equals the number and type of atoms on the product side of the equation.

Reactants Products

Page 15: Chemical vs physical properties

To check for balance, multiply coefficient x subscript

__H₂ + __O₂ __H₂OA. 1, 1, 1B. 2, 1, 2C. 2, 1, 2 D. 2, 2, 2

__K + __B2O3 __K2O + __BA. 3, 2, 3, 2B. 6, 1, 3, 2C. 6, 2, 3, 2D. 3, 2, 2, 2

To balance an equation its cool to change coefficients, do not change subscripts….don’t mess w/the little people (you’ll change the molecule’s identity!)

Page 16: Chemical vs physical properties

1. Calculate the mass of the product of 6.40 g of magnesium with 1.32 g of oxygen .

2. Calculate the mass of the zinc that reacts with 4.11 g of hydrochloric acid to form 9.1 g of zinc chloride and 3.97 g of hydrogen gas.

3. During the combustion of 5.00 g of Butane in the presence of oxygen, 4.01 g of carbon dioxide and 3.55 g of water is given off. How much oxygen was needed to totally combust the butane?

Page 17: Chemical vs physical properties

Review…..

Page 18: Chemical vs physical properties

• Made when two or more elements combine during a chemical reaction

• Examples:• Water• Salt• Sugar

• Chemical Change

Compound:

Page 19: Chemical vs physical properties

What is evidence that a chemical reaction is happening again?

• Fire, Combustion, Explosion

• A new color appears/disappears

• Temperature change• Production of Gas, gas

bubbles• Production of

Precipitates

Compounds are formed or separated through chemical reactions…

Page 20: Chemical vs physical properties

• Combines 2 or more substances without producing a chemical reaction

• NOT the same throughout - heterogeneous

• Can be separated easily

• Examples:• Soil • Fruit salad

• Physical Change

Mixture

Page 21: Chemical vs physical properties

• A type of MIXTURE that IS the same throughout - homogenous

• Solute- substance being dissolved• Solvent- substance doing the dissolving

• Examples:• Salt water • Lemonade

• Physical Change

Solution:

Salt = Solute

Water= Solvent

Salt Water= Solution