Tuesday, July 14, 2009

Homework help for chem?

I have missed my chemistry class a couple days this month because i have been pretty sick. my teacher just gave me a ton of work which i need help with. i have a test soon and i was wondering if anyone could help b/c i dont have the time/money for tutor! thanks any one know anyhing about these topics?!


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)

Homework help for chem?
a pH scale goes from 1 to 14. 7 is neutral (not 7.1 or 6.9, just 7.0). As a number goes lower than 7, it becomes more acidic. The chemicals between 7.1 and 14 are bases. As the number of the pH goes further from 7, the more basic (adjective form of the word base) it is. Your blood is basic and your stomach has acids in it to digest your food. Water is neutral.





The number for a mole is 6.022x10^23 particles of a chemical. It can be used to find the mass of a certain number of particles (atoms, molecules, etc) and is then used as a conversion factor. The conversion factor is written like this:


6.022x10^23 particles = 1 mole





When you predict the products of a chemical reaction, there is a kind called a Single Displacement reaction (1 of the 5 kinds - I'll go into them later). In a Single Displacement reaction, a reaction may or may not occur.


Think of a Single displacement like a dance: You go to a dance with a date and there is a cuter guy/girl you notice that doesn't have a date. You break up with your date and make the cuter guy/girl your date. The atoms in a single displacement reactions (look at the charges of all 3 elements to know which in the compund will stay in a compund). The activity series shows you which elements are "cuter" than others (if the element in the compound is "cuter", no reaction will occur). The "cuter" ones are toward the top.





In an exothermic reaction, heat is released (an example is a match - or burning anything). In an endothermic reaction, heat is absorbed (photosynthesis is an example since the plant absorbs the sunlight).


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