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Chemistry. Chapters 1 and 16. 2 types of chemical rxns :. exothermic- energy is released in the rxn exo - out takes place without help. endothermic- energy is absorbed in rxn endo - in have to have energy in order to occur. Chemistry.

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Chemistry

Chemistry

Chapters 1 and 16


2 types of chemical rxns
2 types of chemical rxns:

  • exothermic- energy is released in the rxn

  • exo- out

  • takes place without help


Chemistry


Chemistry1
Chemistry

  • the study of the composition of substances and the changes they undergo

  • energy is involved in accomplishing these changes



Chemistry


Branches of chemistry
Branches of Chemistry

  • 2 major:

    1. inorganic- concerns substances that are usually without carbon

    2. organic- study of substances containing carbon

    subst from living things


Types of research
Types of research:

1. basic research- carried out for the sake of increasing knowledge

chance discoveries can occur and have changed our lives!


Chemistry

2. applied research- carried out to solve problems

depletion of ozone layers by CFCs led scientists to develop new refrigerants



Matter
Matter that improve our quality of life

  • Which of the following could be called matter?


Matter1
Matter that improve our quality of life

  • anything that has a volume and a mass

    • mass- measure of the amount of matter

      use a balance to measure

    • volume- amount of space a 3D object takes up


Chemistry

  • many forms of matter that improve our quality of life

  • fundamental building blocks of matter:

    • atoms and molecules

      What’s the difference?


Chemistry


Chemistry


Chemistry

  • compound- chemical identity of that elementsubst that can be broken down into simpler, stable subst

    • usu made from 2 or more kinds of atoms


Properties of matter
Properties of Matter chemical identity of that element

  • used to distinguish between subst and to separate them

  • help to reveal unknown subst

  • ALL matter has many properties by which it can be grouped

  • properties are either intensive or extensive


Intensive properties
Intensive Properties chemical identity of that element

  • do NOT depend on the amount of matter examined

  • same for a 0.5g sample as 500kg sample

  • ex: melting point, boiling point, density, conduction of electricity


Extensive properties
Extensive Properties chemical identity of that element

  • DO depend on the amount of matter present

  • there will be a difference in a 0.5g sample and a 500kg sample

  • ex: volume, mass, amount of energy in sample


Chemistry


Chemistry

2. chemical identity of that elementChemical properties- prop that matter exhibits as it undergoes changes that transform it into different subst

easiest to see as matter reacts to form new subst

ex: reactivity with oxygen, flammability


Matter frequently goes thru changes 2 types of changes
Matter frequently goes thru changes chemical identity of that element2 types of changes:

1. physical chg- a change in a subst that does NOT involve a chg in the identity of the subst

ex: melting, boiling, grinding, tearing, cutting


Chemistry

2 chemical identity of that element. chemical changes- aka chemical reactions- a chg in which the subst is converted into different subst

ex: rusting, tarnishing, burning


Chemistry

  • some chemical identity of that elementphy chg are part of an important class of chgs called change of state

    • phy chg of a subst from one state to another

    • 4 main states of matter:

    • STATES OF MATTER FOLDABLE


Chemistry

2 chemical identity of that element. chemical changes- aka chemical reactions- a chg in which the subst is converted into different subst

ex: rusting, tarnishing, burning


Chemical rxn
Chemical chemical identity of that elementRxn

magnesium plus oxygen yields magnesium oxide

Mg + O2 MgO

parts of chemrxn:

1. reactants- the substances that react in the chemrxn

arrow points AWAY FROM reactants


Chemistry

2. chemical identity of that elementproducts- the subst that are formed by the chem chg

arrow ALWAYS POINTS TO products

3. arrow stands for yields

ex: p. 10 fig.7


Energy
Energy chemical identity of that element

  • ALL changes (physical OR chemical) will involve energy

  • can be different forms, like heat and light

  • boundaries between phy and chemchgs are not always very clear

  • in any chg, the total amount of energy involved DOES NOT change

  • the Law of conservation of energy


Classification of matter
Classification of Matter chemical identity of that element

  • tremendous variety of forms of matter

  • can be categorized into 2 groups:

    1. pure substance- composition is same thruout

    • can be elements or compounds

      2. mixture- contains more than 1 subst; can vary in composition and properties


Pure substances
Pure Substances chemical identity of that element

  • every sample has a fixed composition

    • H2O (by mass, 88.8% O and 11.2% H)

  • every sample has exactly the same characteristic properties

  • properties can be used to identify the subst

  • either elements or compounds


Mixtures
Mixtures chemical identity of that element

  • blend of 2 or more kinds of matter, each retaining its own identity and properties

  • usu physically combined and can be separated

  • properties of mixture are a combination of the properties of subst that make it up

  • 2 types of mixtures:


1 homo geneous mixtures
1. chemical identity of that elementhomogeneous mixtures

  • homo- same

  • looks the same thru-out

  • uniform in composition

  • aka- solutions

  • may be solids, liquids, gases


2 parts to a soln
2 parts to a chemical identity of that elementsoln:

  • solvent- part that does the dissolving

    usu water

    aka- the universal solvent

2. solute- part that is dissolved


2 hetero geneous mixture
2. chemical identity of that elementheterogeneous mixture

  • hetero- different

  • may look different

  • composed of more than one phase

  • separated by boundaries called interfaces


Elements
Elements chemical identity of that element

  • substances composed of only one kind of atom

  • ALWAYS have the same composition

  • ex: gold, mercury, hydrogen


Compounds
Compounds chemical identity of that element

  • substances composed of more than one kind of atom always arranged in definite ratios

  • ex: copper II sulfate, CuSO4

  • sucrose, C12H22O11


In chemical changes
In chemical changes: chemical identity of that element

  • one or more subst are used up

  • 1 or more new subst are formed

  • energy is absorbed or released


Evidence of chemical changes
Evidence of chemical changes: chemical identity of that element

  • color change

  • formation of precipitate (ppt)


Chemistry

  • gas bubbling chemical identity of that element

  • energy changes- heat, light


2 types of chemical rxns1
2 types of chemical chemical identity of that elementrxns:

  • exothermic- energy is released in the rxn

  • exo- out

  • tend to take place without help


Chemistry

  • endothermic chemical identity of that elementrxn- energy is absorbed in the rxn

  • endo- inside

  • have to have input of energy to occur


Physical changes
Physical Changes chemical identity of that element

  • occur with NO changes in the composition

  • can be:

    • chgs of state

    • cutting/breaking

    • dissolving

    • distillation

    • fractional crystallization


Energy1
Energy chemical identity of that element

  • phy and chemchgs ( ) always accompanied by energy changes

  • energy changes occur betw sys and surroundings

  • energy transfer as a result of temp difference is HEAT

  • can measure energy chg using units called Joules (J)


Chemistry

  • older unit used is calorie chemical identity of that element

  • 1 cal = 4.184 J

  • food calorie is a larger unit

  • 1 CAL = 1 000 cal

  • convert betw units


Thermochemistry
Thermochemistry chemical identity of that element

  • study of the transfer of heat energy that accompany chemrxns and physical chg

  • temp- is a measure of the average kinetic energy of the particles in a sample of matter

  • greater KE, higher temp, hotter it feels


Chemistry

  • K= chemical identity of that elementoC + 273

  • HEAT- measure of the total amount of kinetic energy of the particles in a sample of matter

  • ALWAYS moves from matter at a higher temp to matter at a lower temp

  • fig 1, p.532



Specific heat
Specific Heat during

  • Will you take a piece of the crust with your finger?

  • Will you stick your finger into the filling of the pie?

  • Why won’t you?

  • Is there a difference?


Chemistry


Chemistry

  • use the formula: other materials

    q = m x Cp x Temp

    heat = mass x specific heat x (Tf-Ti)

    when heat is gained, Tf-Ti

    when heat is lost, Ti-Tf


Chemistry

ex: How much heat energy is needed to increase the temp of 755g of Fe from 283oC to 403oC?

How much energy must a refrigerator absorb from 225g of water so that the temp of the water will drop from 35.5oC to 5.0oC?

What mass of water is required to absorb 470 000J of energy from a car engine while the temp increases from 25.0oC to 82.5oC?

Apiece of copper alloy with a mass of 85.0g is heated from 30.0oC to 45.5oC. In the process, it absorbs 523J of heat. What is its specific heat?


Chemistry

ex: How much heat energy is needed to increase the temp of 755g of Fe from 283oC to 403oC?

How much energy must a refrigerator absorb from 225g of water so that the temp of the water will drop from 35.5oC to 5.0oC?


Chemistry


Chemistry


Measuring temp
Measuring Temp other quantity of matter in a system

  • If a piece of gold with amass of 45.5g and a temp of 80.5oC is dropped into 192g of water at a temp of 15.0oC, what is the final temp of the system?