Substances are composed of atoms and elements Substance is matter that has the same fixed
composition, can’t be broken down by physical processes
Physical processes: boiling, changing pressure, cooling, or sorting
Chemical process: change the original substance into new substance(burning, chemical reactions, reaction to light)
REVIEW :Atom have specific protons for each element
Two or more elements chemically combined in specific combinations and composition
H2O, NaCl, H2SO4, Water, salt, sulfuric acid
Mixtures are combinations of substances that are not bonded together and can be separated by physical processes (salt water, granite, salt and pepper)
Heterogeneous Mixtures: mixture where substances are not mixed evenly
◦ Areas have different compositions◦ Seeds in watermelon, minerals in granite, cereal in milk
Homogeneous mixtures: contains 2 or more substances that are evenly mixed but are not chemically bonded together
Shampoo, sugar water, Kool-Aid are examples
Solutions is another name for homogeneous mixtures
Solutions form when a solute (salt) dissolves in a solvent (water)
Forming solids from a solution◦Crystallization occurs when cooling or
evaporation takes place and leaves a solid◦Precipitates forms from a chemical reaction that
produces a substance that isn’t soluable in solution and drops out
Liquid solid solutions: solid (solute) dissolves in liquid(solvent) salt in water
Liquid gas solutions: gas is dissolved in a liquid (gas dissolved in water: carbonated water)
Liquid-liquid solutions: both solute and solvent are liquids ( vinegar and water)
Smaller amount of one gas (solute) is dissolved in a larger amount of gas (solvent)
Both solvent and solute are gases◦Example: Our atmosphere contains 78%
Nitrogen and would be the solvent and other gases in atmosphere would be the solute
In solid solutions, the solvent is a solid
Solute can be a gas, liquid, or solid
Solid-solid solution: alloys are mixture of 2 or more metals melted together and mixed (brass, steel)
Water the Universal Solvent
◦Aqueous refers to a solution of where water is the solvent
◦Water can dissolve may different solutes
Molecular Compounds:
◦Water is formed by sharing electrons between 2 atoms of H and 1 atom of Hydrogen
◦Water molecules when combined have areas of electrical charges that attract opposite charges, thus are polar charged
When compounds are formed by gaining or losing electrons to bond elements together
When atoms gain and lose electrons the number of electrons change and give an overall charge on the atoms
Opposite charge atoms attract and hold each other together
Because of the polar charge of water areas of water molecules attract the charged particles of ionic compounds and break them up
(Page 627 figure 8)
Water molecules moves in between sugar molecules and separate them (thus dissolving)
What will dissolve?Like dissolves like
◦Polar solvents dissolve polar solutes (salt and water)
◦Nonpolar solvents dissolves non polar solutes
If you have a polar molecule and nonpolar molecule (unlike polar molecules) they will not dissolve and will not form a solution
Oil is a nonpolar molecule that will not mix with polar water, therefore these two substances will no form a solution
Solubility is a measurement of how much a solute will dissolve in a given amount of solvent
It is described as how much solvent can be dissolved in 100 ml of solvent at a certain temperature
At 25@ C grams dissolved in 100 ml wataer
Potassium chromate
63 g
Barium sulfide .00025 g
Liquid solid solutions: temperature affects how much solutes can be dissolved
Usually an increase in temperature allows more solute to be dissolved◦Notice on chart that NaCl and CaCO3
become less soluble in higher temperatures
Liquid-gas solutions: increase in temperature decrease the solubility of a gas dissolved in it
Carbon dioxide is dissolved under pressure in water in pop cans
◦Opening a warm can of pop vrs a cold can, the gas is released much faster and leaves the solution under warmer conditions faster
A saturated solutions can hold no more solute in solution at a given temperature or pressure
It will fall to bottom of solvent A hot solution can hold more solute than
at lower temperatures and when cooling the hot saturated solution a supersaturated solution may form
Rate of dissolving is sped up by: ◦Increasing temperature◦Crushing the solute◦Stirring the solution
Concentration of a solution tells you how much solute is present compared to the amount of solvent◦It is recorded by using percent of solute is
compared to solvent◦Juices concentration are written by 15%,
20% etc
When a solute is added to water (salt water) and you want to freeze it , a lower temperature is needed (to freeze salt water could be 31℃)
If you want to boil salt water a greater temperature is needed to boil it
Acids: are substances that release positive H+ ions in water called a hydronium ion
When an acid mixes with water, acid dissolves and releases H+ ion
Sour taste
Conduct electricity
Corrosive (break down substances)
React strongly with metals releasing H gas
Vinegar (acetic acid), citric acid, ascorbic acid we are familiar with
H2SO4 (sulfuric acid) ◦ Production of fertilizers, batteries, paint
HCl (hydrochloric acid) ◦ Muratic acid used in pickling that removes impurities from
the surfaces of metals, cleans motar, bricks HNO3 (nitric acid) use in fertilizer, dyes, and plastic
Bases are substances that accept H+ ions and give off to a solution of water with OH- ions
Feels soapy, slippery Taste bitter Corrosives Conduct electricity
Cleaning productsYour blood is basic in solutionNaOH (sodium Hydroxide) is known as
lye and is used to make soap, clean ovens, unclog drains
CaOH (calcium hydroxide) often called lime is put on athletic fields to mark lines
pH is the measure of how acidic or basic a solution is Ranges from 0-14 where neutral pH is at 7 Below 7 covers the range of acid solutions (closer to 0
is more acidic0 Above 7 covers range of basic solutions (closer to 14 is
more basic)
Some acids are helpful (HCl in stomach to digest food however too concentrated HCl will eat away on tissue
If more H+ (hydronium ions) are present the higher the acidic content (lower pH)
Bases with large amounts of OH- ions (hydroxide) have greater concentrations and are more basic (higher pH)
Each number on pH is 10 fold greater or smaller than the number before it:
Comparing ph3 to ph1 is a difference of 2 2 102 means that there is a difference of
100 times more acidic
Indicators are compounds that react with acidic and basic solutions and produce certain colors to indicate their acidity or basicity tendencies
Neutralization is the reaction of an acid with a base
When an acid and a base are combined, they will neutralization each other and the resulting pH will be 7
NaOH + HCl NaCl + H2O Base acid salt water