have missed my chemistry class for acouple weeks b/c i have been sick. my teacher just gave me a ton of work which i need help with. can you teach me about these topics please??
thankss
What is the purpose of the actvity series?
What is the mole(value, what it is used for)?
Discuss the Gas Laws- (Boyle, Charles, Ideal)
Discuss endothermic/exothermic reactions.
What are reactions at equilibruim?
pH scale --acid base and neutral(examples)
2007-02-02 08:33:10 · 3 answers · asked by nice too meet you. 4 in Science & Mathematics ➔ Chemistry
An activity series is a list of elements with the most active on the top and the least active on the bottom. It helps us determine whether or not a reaction should occur when we mix two chemicals together. EX: Zn + H2SO4 --> ? If you look at the activity series of metals, Zn is higher than H. This means that Zn will react with the acid to release H2 gas and produce ZnSO4. If the pure metal is higher than the metal in the compound the reaction will occur. If the pure metal is lower the reaction does not occur.
A mole is a measurement unit that compares the number of atoms or molecules present. It is a concept first proposed by Avogadro. He determined that one mole of any substance is equatal to the mass of that substance measured in grams. EX: one mole of Na = 23 g Na; 1 mol Ca = 40 g Ca; 1 mol H20 = mass of 2 H and 1 O added together = 18 g.
The mole is an important concept in chemistry. It allows us to convert the mass of a substance into the number of particles of that substance. One mole of anything = 6.02 x 10^23 particles. To give you an idea of how many particles that would be imagine these things - 1 mol of baskeballs put together would be a pile of basketballs the size of the Earth. 1 mol of eggs put together would cover the surface of the Earth to a depth of 1 km.
By comparing the numbers of atoms or molecules instead of masses we can account for the correct proportions when combining things in a chemical reaction.
Gas Laws -
Boyles - compares the volume of a gas to the pressure on that gas. The more pressure-the smaller the volume. The higher pressure squeezes the atoms closer together. The equation to calculate the pressure or volume is
P1V1 = P2V2 The pressure x volume and the beginning is equal to the pressure x volume at the end.
Charles' Law -
Compares the temperature of the gas to the volume of the gas. As the temperature increases the atoms move faster and bounce farther apart so the volume increases. The equation for this law is
V1/T1 = V2/T2 the first volume divided by the first temperature is equal to the final volume divided by the final temperature. NOTE--you must convert Celsius temperature into Kelvin temperature by adding 273. Kelvin temperature is known as absolute temperature. We must use this temperature because 0 K is the lowest possible temperature (absolute zero) and there are no negative numbers on the Kelvin scale.
Ideal Gas Law -
If all three things--temp., pressure, and volume are changing we combine both laws to get this one
P1V1/T1 = P2V2/T2 remember to change the temperature to Kelvin
Endothermic reactions are those which require heat in order to proceed. If energy is not put into the reaction it will not occur.
Exothermic reactions release heat. An example of this is buring wood. You must add a small amount of energy (activation energy - a match or lighter) to get the reaction started, but then more heat is released once the reaction gets started.
A reaction at equilibrium is one where the rate of formation of the products is equal to the rate of the reverse reaction where the products separate into the reactants again.
pH is a scale to measure the acidity of alkalinity of a solution. The scale goes from 1 to 14. Acidic solutions range from 1 to 6 while basic solutions range from 8 to 14. A neutral solution has a pH of 7
pH is really related to concentration of H+ ions in the solution.
pH = -log[H3O+] this tells us that the greater the H+ - or H3O+ - of the solution the stronger the acid. HCl is an acid. It has a low pH. NaOH is a base. It has a high pH. Pure H2O is neutral. It has a pH of 7.
2007-02-02 08:42:31 · answer #1 · answered by physandchemteach 7 · 0⤊ 0⤋
There's a lot of information to learn here so it will take a while...
The activity series is the likeliness that a metal will react with another substance. It's kinda long and I don't remember it off the top of my head, but any information site will have the full list.
The mole (abbreviation = mol) is most commonly used in stoichiometry conversions. It is also a very common unit of measurement in most chemistry.
There are several ways to find mols. If you are given the mass (g) of a substance, use to molar mass of the substance to find mols.
(Molar mass is the combined weight of each of the parts of the substance.)
The conversion would look like such:
(# grams of substance/ molar mass of substance) = moles of substance
Another conversion of moles is from liters.
(# L of solution/22.4) = moles of solution
The final common conversion for moles is to/from atoms/molecules/ions (all are the same value). The conversion is:
(# atoms/ 6.022 * 10^23) = moles
(6.022 * 10^23 is Avagadro's number, you will need it for the rest of your chemistry carreer. Don't forget it.)
The mol has several uses. In a chemical equation, the mole is the coefficient of each molecule involved. The mole is also needed in finding molarity, molality, change in temperature, and many more chemical equations.
Gas laws:
(P, pressure, is always in atm; V, volume, is in liters; T, temperature is in Kelvin; R is a constant and equals .08206; k is a constant, n is the number of moles.)
Boyle's gas law states that the pressure and volume of a gas, at a constant temperature, are constant. This means that P and V are inversely proportional. Meaning
PV = k (when k is a constant)
This also means that at a constant pressure
P1V1 = P2V2
Charles's law relates volume and temperature and shows them to be directly proportional. Such that:
V/T = k
and at a constant pressure:
V1/T1 = V2/T2
The ideal gas law states that pressure and volume are equal to temperature, moles, times the rate constant.
PV = nRT
This of course, only works in ideal hypothetical situations. There is a corrected gas law (highly complex) for actual behavior of gases under conditions.
Rxns:
Endothermic reaction: Heat is absorbed, reaction feels cold to the touch, more energry is used than is given off
Exothermic: Heat is given off, feels warm to the touch, more energy is given off than is used in the reaction
pH scale judges the acidity or basic nature of solutions. The pH scale ranges from 1-14. 1 is the most acidic, 14 the most basic, 7 is neutral.
Acids are usually sour and bases are usually bitter. Common acids include carbonate soda, lemons, and hydrochloric acid. Common bases include detergent, soap, and most household cleaning products. Water is relatively neutral.
Combining a strong acid with a strong base will yield water (a neutral solution) and a precipitate (a solid). This can be called a precipitation reaction, an acid-base titration, or a neutralization reaction. This occurs because the acidic part of an acid is hydrogen (H+) and the basic part of a base is hydroxide (OH-) These parts combine to form HOH or H2O, water.
Just tell me if you need anything else further explained.
2007-02-02 08:39:57 · answer #2 · answered by JEBalke 2 · 0⤊ 0⤋
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2016-05-24 06:02:47 · answer #3 · answered by ? 4 · 0⤊ 0⤋