exam 2

polyatomic ion definition common ions

-ion made up of more than one atom. Some ionic compounds contain polyatomic ions. The atoms forming a polyatomic ion are bound together by covalent bonds, with the cluster as a whole bearing a positive or negative charge Ammonium NH4+1 Bicarbonate HCO3-1 Carbonate CO3-2 Hydroxide OH-1 Nitrate NO3-1 Nitrite NO2-1 Phosphate PO4-3 Sulfate SO4-2

when naming covalent compounds...

-the first nonmetal in the formula is named by its element -the second nonmetal is written second and ends in -ide -the nonmetal always has a prefix, (monoxide, dioxide) and the metal only has a prefix if there is more than one

when naming an ionic compound...

-the name of the metal is written first and is the same name as the element -the name of the nonmetal is written second and ends with -ide -transition metals except for zinc (+2), ag (+1), and ag (+2) form two or more cations (positive) -a roman numeral equal to the ion charge is placed in parentheses immediately after the metal name. The cation charge is equal to the anion charge.

7.3 1. Define solution molarity. 2. Explain how percentage concentrations are used to describe common solutions. 3. Explain what units are used to express exceedingly small concentrations.

1. (DO PRACTICE PROBLEMS!!) molarity (M) is moles / liter. to get molarity divide the amount of moles in the solution by the volume in liters. if 1.5 moles of solute is dissolved in 0.4 liters, divide them to get 3.75 M to determine number of moles in solute, multiply the volume in liters by its molarity (moles over liters) 0.4 L x (3.75 mol / 1 liter) = 1.5 moles to find volume multiply moles of solute by molarity (liters over moles) to get volume. 1.5 moles x (1 L / 3.75 moles) = 0.4 L if you want to prepare a specific volume of a solution of known molarity. if you want to prepare 5 L of a 0.154 M NaCl solution 5.0 L x (0.154 moles / 1 liter) = 0.77 moles 0.77 moles x (58.5 g NaCl / 1 mol) = 45g NaCl 2. percentage typically means # of grams per 100g. 5% NaCl would mean 5g NaCl per 100g of solution. Or it is volume / volume percentage (v/v). 70% v/v solution means 70mL in every 100mL of solution. 3. we still use percentage for small parts. parts per thousand or parts per million. 0.3% would mean .3 out of 100, or 3 per 1,000. parts per million is equal to 1 mg (1,000 mg = 1g) in a 1 kg solvent (1,000g = 1 kg)

3.5 1.Define organic chemistry. 2. Recognize the structure of alkanes and describe how to name them.

1. Organic chemistry is chemistry dealing with organic compounds, which are compounds containing carbon. 2. alkanes are hydrocarbons containing only single bonds. HOW TO NAME ALKANES -figure out how many carbons from prefix. -take number of carbons x 2, and then add two to get number of hyrdrogens -number of carbon atoms is Butane = 4 Carbons (4x2) + 2 = 10 Hydrogens C4H10

7.1 1. Identify the basic components of a solution. 2. Describe how water acts as a solvent. 3. Explain how colloids and dispersions differ from solutions.

1. The solution is the mixture of two or more substances, the solvent is the substance in greater amount in the solution (like water), and the solute is the substance in a lesser amount and dissolves in the solution. 2. 3. A colloid is a stable dispersion of fine particles of one substance in another. To tell if a substance is a colloid or solution shine a light through it. A light shone through solution will have no noticeable effect, but you can see the beam through a colloid. (fog and soapy water are colloids)

6.3 1. Describe how chemical changes differ from physical changes. 2. Explain how to balance a chemical equation.

1. a chemical change produces substances with new chemical compositions. physical changes change their form (liquid, solid, gas), but don't alter their composition. 2.(DO PRACTICE PROBLEMS!!) must be the same number of atoms on right and left of arrow in chemical equation using coefficients (start with carbon or hydrogen atoms first) if you have to use a non whole number (like 6.5) as a coefficient, do it and then multiply the ENTIRE equation by 2. - [ C4H10 + 6.5O2 --> 4CO2 + 5H20 ] x 2 = 2C4H10 + 13O2 --> 8CO2 + 10H20

7.2 1. Describe Henry's Law. 2. Provide common examples of gases dissolved in liquid

1. at a constant pressure, the amount of gas dissolved in a liquid is directly proportional to the pressure of gas above the liquid. forms the basis of how water is carbonated and why if it is left open it goes flat. 2. gases into and out of our bloodstream like oxygen and co2, or blood acohol content.

6.2 1. identify the gases in our atmosphere and the basis for atmospheric pressure. 2. Describe how the volume of a gas changes with changes in pressure and temperature. 3. Explain how the expansion of gases can be used for cooling purposes.

1. at sea level, nitrogen makes up 78%, oxygen 21%, and argon and other trace gases 1%. atmospheric pressure varies with altitude and weather conditions. pressure drops with altitude. the combined weight of all the gases above any particular point, either on Earth's surface or anywhere within the atmosphere itself, generates the atmospheric pressure at that spot. 2. (DO PRACTICE PROBLEMS!!) boyle's law - at a constant temperature, pressure and volume are opposites. when one increases, the other decreases and vice versa. P1V1 = P2V2 charles law - gas pressure is proportional to temperature. P1/T1 = P2/T2 combined gas law = [ (P1 x V1) \ T1 ] = [(P2 x V2) \ T2 ] remember, you HAVE TO CONVERT CELSIUS TO KELVIN (add 273) 3. gases release heat when they are compressed, and absorb heat from the environment when they expand. example, referigerator coolants go through a process of compressing and expanding. gases go through coils inside the fridge and expand to cool it, and then go through coils outside the fridge and are compressed to release heat.

6.1 1. Describe what happens at the molecular level when a substance changes from one state to another. 2. Compare densities of common substances and explain how density can change with temperature.

1. for example - solid ice. when you put heat into it the molecules absorb the energy. when these molecules hit their melting point the molecules are moving enough to break from their fixed position. when they begin to move freely, you can see the solid turning into a liquid. liquids still experience intermolecular force, but have enough energy to move around out of their fixed position. if you add even more energy they break away even more as the liquid turns to a gas once they hit their boiling point. the process goes backwards if you are removing energy. sublimation is skipping the liquid state. 2. density is how much mass is in a given volume of a substance. density = mass / volume. a substance is most dense as a solid, a little less dense as a liquid, and far less dense as a gas. density decreases when you add heat because of thermal expansion. So its the same mass occupying a greater volume. So when temperature deceases, density increases.

3.4 1. Describe how the structures of molecules are depicted. 2. Show how to write a molecular formula, calculate molecular mass, and name simple covalent compounds. 3. Describe how covalent compounds differ from ionic compounds.

1. the arrangement in space of the atoms that make up the molecule 2. molecular mass- sum of atomic masses molecular formula- chemical formula of a covalent compound. alphabetical order (C10H18O18 = 10 carbons, 18 hydrogens, 18 oxygens.) naming simple covalent compounds- the name tells you what it contains and how many of each element. (CO2 = carbon dioxide, NO3 = nitrogen trioxide, N305 = trinitrogen pentoxide, ) 3. Covalent compounds exist as discrete molecular units, as opposed to ionic compounds, which exist as a regularly ordered array (crystal lattice) of ions that extends out in space. -The atoms in the molecules of covalent compounds are held together by covalent bonds. In ionic com- pounds, the ions of the crystal lattice are held together by ionic bonds. covalent compounds have lower melting points, have a stronger odor, lower conductivity, and aren't very soluble

6.4 1. Explain how the mass of a pure substance relates to the number of chemical particles it contains. 2. Using a balanced equation, determine the amounts of reactants consumed or products formed in a chemical reaction. 3. Calculate the amount of heat released in a combustion reaction

1. the molecular or atomic mass of a substance is equal to one mole, which is 6.02 x 10^23 atoms, particles, or molecules. 1 mole of carbon = 12 g... same amount of atoms as 1 mole of neon gas =20 g 2. (DO PRACTICE PROBLEMS!!) coefficients in balanced equation also refer to moles of substance. use mole ratio to help determine amounts. for example, for every 1 mole of c3h8 that reacts, 5 mol o2 is consumed, 3 mol c02 are produced, and 4 mol h20 is produced. how many moles of c02 are produced if we use 12 moles of c3h8? (use mole ratio) 12 mol c3h8 x (3 mol co2 / 1 mol c3h8) = 36 mol c02 if 50 moles of h20 are produced, how many moles of c3h8 reacted? 50 moles h20 x (1 mol c3h8 / 4 mol h20) = 12.5 mol c3h8 3. if there is less energy produced than there is in the reactants, the excess gets released to the environment. use the heat of combustion (kcal) to determine the amount. for example, for every mole of propane (c3h8) that burns, 531 kcals of energy is released. a typical 20 lb tank of propane contains 207 moles of propane. how much energy is released? 207 mol c3h8 x (531 kcal \ 1 mol c3h8) = 109,917 kcal

7.4 1. Appreciate that fresh water is a relatively scarce resource. 2. Understand that fresh water naturally contains dissolved substances. 3. Define polluted water. Describe how fresh water can be produced from salt water

1. water is dispersed over about 70% of the earth's surface. 97.5% of it is salt water, most of the freshwater is inaccessible. only 0.3% of water is readily accessible and can be drank. 2. purest water comes from chemist's labs. tap water comes from reservoirs of groundwater. groundwater runs off from rivers, lakes, rain, porous rocks... etc. 3. polluted water is water that contains chemicals that are harmful to us, such as arsenic, mercury, and lead. maximum contaminant levels keeps harmful toxins out of our drinking waters by law. through desalination we can removed salt from water using the reverse osmosis process. high pressure is applied to salt water in contact with a semipermeable membrane. this applied pressure overcomes force of osmosis causing nearly pure water to pass through the membrane.

what is polar

Having a separation of charge due to differences of electronegativities of component atoms or ions.

how to name in hydrocarbons

IUPAC SYSTEM FOR NAMING CHAINS (DO PRACTICE PROBLEMS!!) 1. find longest carbon chain 2. identify groups attached to main chain and number them starting with lowest number 3. indicate other groups with prefix number 4. give each group on chain its individual location number 5. separate numbers by commas, and numbers from letters with hyphen 2,2,4-trimethylpentane means there is a chain of 5 carbons, 3 methyl groups loacted at 2, 2, and 4

diatomic molecules

N2, O2, H2, F2, Cl2, Br2, I2

emulsion

a colloid where micropatricles of one polarity suspended in a liquid of another polarity (oil on water)

what is a hydrogen bond?

attractive force between a oxygen, fluorine, or nitrogen on separate molecule to a hydrogen bonded to a oxygen, fluorine, or nitrogen

what is intermolecular force? what is dispersion force?

attractive force between molecules in close proximity. molecules with higher intermolecular force have higher melting and boiling points dispersion force is a weak attraction between nonpolar molecules in close proximity

temperature affect

colder temp liquids can hold more gas than hotter temperatures

external pressure affect

high pressure above the liquid will force more gas to dissolve into the liquid

first 10 straight chain alkanes (memorize!!!!)

methane CH4 ethane C2H6 propane C3H8 butane C4H10 pentane C5H12 hexane C6H14 heptane C7H16 octane C8H18 nonane C9H20 decane C10H22

nucleation

process that initiates formation of a distinct state of matter in solution like bubbles

how do molecules move

solids- vibrate or rotate but don't move liquid- not in fixed position and move some gas- move around everywhere, no attraction between molecules

what are isomers?

two or more compounds that share the same molecular formular but differ in structure