Properties of MatterProperties and Changes

Section 3.1

Matter = Substance: matter that has a uniform and unchanging

composition, aka pure substance Mixture: two or more substances that have been

combined and each substance retains its own chemical identity (sugar + flour)

Pure Substances Impure Substance (mixture)

distilled water ocean = water + salt

What is Matter?

Substance – matter that has a uniform and unchanging composition Example: salt – NaCl

Physical properties – characteristics that can be observed or measured without changing the composition of the sample

viscosity hardness densityconductivity melting point

colormalleability boiling point odor

Physical Properties

1. Extensive properties – dependent on the amount of substance present

2. Intensive properties – independent of the amount of substance present

2 Types of Physical Properties

Some of the properties of a material change, but the substances in the material remain the same; chemical composition remains the same; some are reversible heating butter crumpling paper slicing a tomato wrinkly shirt/iron hair braiding peeling oranges Change of state

Ice-melting liquid

Recognizing Physical Changes

Physical Separation of substancesmagnetic propertiescrystallization/evaporation

filtration chromatography

distillation manual separation

Physical Separation of Substances

Materials can be classified as solids, liquids, gases, or plasma based on whether their shapes and volumes are definite or variable

Shape and volume are clues to how the particles within a material are arranged

Phases of Matter

Definite shape and volume Atoms are packed close together and have

an orderly arrangement of particles Changing the container doesn’t change the

shape or volume of a solid Examples: pencil, cafeteria tray, book,

quarter

Solids

Definite volume and take the shape of its container

Can be poured, will take on a new shape Atoms are close together, but their

arrangement is more random than those of a solid

Examples: juice, water, mercury, honey

Liquids

Does not have a definite shape nor a definite volume

Takes the shape and volume of its container Atoms are not arranged in a regular pattern

and can have a big space between them COMPRESSIBLE Examples: Air, helium, natural gas

Gases

Ionized gas with enough energy to have free electrons lightning sun neon signs

Plasma

solid

liquid

gas

plasma

Kinetic Energy of Phases of Matter

Particles Shape VolumeCompressible?

Solid Very close together, orderly arrangement

Fixed Fixed No

Liquid Close together but not as orderly as solid

Changes Fixed No

Gas Lots of space between, no order

Changes Changes Yes

Chemical properties – the ability of a substance to combine with or change into another substance Iron + O2 -> Rust (FeO) Burning Cooking CO2 + H2O -> C6H12O6 + O2

EVERY SUBSTANCE HAS A UNIQUE SET OF PHYSICAL AND CHEMICAL PROPERTIES

Chemical Properties

A useful description of a chemical reaction tells you the substances present before and after the reaction

Reactants undergo the change and the new substances that are formed are the products

Reactants Products

Chemical Equations

Evidence of chemical changes include: Change in color – leaves on trees, banana peel, copper,

silver Production of gas (bubbles) – vinegar and baking soda,

cake baking

Formation of a precipitant – acid + milk (protein goes through chemical change), cottage cheese Production of light Temperature Change – reaction causes heat to be given off or absorbed (gets cold)

Endothermic Exothermic

Recognizing Chemical Changes

Law of Conservation of Mass

Mass is neither created nor destroyed

Mass reactants = Mass products

Reactants ProductsH2O + O2 H2O

18 grams + 22 grams ? H2O

1. Write what you know• chemical reaction• reactants and their masses• products and their masses

2. What are you solving for?3. Solve for your unknown

Steps to Solve Law of Conservation of Mass Problems

1. From a laboratory experiment designed to separate water into hydrogen and oxygen gas, a student collected 10.0 g of hydrogen and 79.4 g of oxygen. How much water was initially involved in the process?

Practice!

Law of Conservation of Mass says…

Mass reactants = Mass of Products

H2O mass = H2 mass + O2 mass

H2O mass = 10.0 g + 79.4 g

H2O mass = 89.4 g

Chemical Reaction

H2O H2 + O2

Reactants Products

What do we know?

H2 = 10.0 g

O2 = 79.4 gWhat is our unknown?

H2O = ??? g

More Practice!

2. A student carefully placed 15.6 g of sodium in a reactor supplied with an excess quantity of chlorine gas. When the reaction was complete, the student obtained 39.7 g of sodium chloride. How many grams of chlorine gas reacted?

Law of Conservation of Mass says…

Mass reactants = Mass of Products

Sodium mass + Chlorine mass = Sodium Chloride mass

15.6 grams + ? grams = 39.7 grams

? grams = 24.1 grams of Chlorine

Chemical Reaction

Reactants Products

Sodium + Chlorine Sodium Chloride

What do we know? Sodium = 15.6 g Sodium Chloride = 39.7 g

What is our unknown? Chlorine = ??? g

3. In a flask, 10.3 g of aluminum reacted with 100 g of liquid bromine to form aluminum bromide. After the reaction, no aluminum remained, and 8.5 grams of bromine remained unreacted. How many grams of compound were formed?

Law of Conservation of Mass says…

Mass reactants = Mass of Products

Aluminum used+ Bromine used = Aluminum Bromide made

10.3 grams + 91.5 grams = ??? grams

101. 8 grams = ? Grams of Aluminum Bromide

Practice!

Chemical Reaction

Reactants Products

Aluminum + Bromine Aluminum Bromide

What do we know? Aluminum = 10.3 g Bromine = 100 g Bromine left over = 8.5 g Bromine used = ??

= 100 – 8.5 g = 91.5 g

What is our unknown? Aluminum Bromide = ??? g

4. A 10.0 g sample of magnesium reacts with oxygen to form 16.6 g of magnesium oxide. How many grams of oxygen reacted?

5. If 50 grams of sodium reacts with chlorine to form 126 grams of salt, how many grams of chlorine reacted?

6. If 20 grams of aluminum reacts with 200 grams of bromide to form aluminum bromide, and no aluminum is left after the reaction, but 23 grams of bromine remained unreacted how many grams of aluminum bromide were formed?

Practice!

7. If 178.8 g of water is separated into hydrogen and oxygen gas, and the hydrogen gas has a mass of 20.0 g what is the mass of the oxygen gas produced?

8. From a laboratory process, a student collects 28.0 g of hydrogen and 224.0 g of oxygen. How much water was originally involved in the process?

Practice!

9. A student carefully placed 23.0 g of sodium in a reactor with an excess quantity of chlorine gas. When the reaction is complete, the student obtained 58 grams of salt. How many grams of chlorine reacted?

10. A 10 gram sample of iron reacts with oxygen to form 18.2 grams of ferric oxide. How many grams of oxygen reacted?

Practice!