stoichiometry

stoichiometry - Chemical Reactions Mass Relationships Some...

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Page ‹#› Chemical Reactions: Mass Relationships Some assumptions I am making: You: can differentiate between an atom and a molecule --given a picture or a formula know the implications of atomic weight (or mass) of an element. can enumerate the # of protons, and # electrons for any element--given the name or symbol of the element. Chemical Reactions: Mass Relationships Some assumptions I am making: You can define and give an example of a mole of a substance--given the formula . You can calculate the mass of 1 mol of a substance or 1 molecule of a substance--given the formula. Chemical Reactions: Mass Relationships Some assumptions I am making: Given a formula, you can calculate a % composition. Let’s see what you can do now! What is the %C in Calcium carbonate (CaCO 3 )? Chemical Reactions: Mass Relationships Some assumptions I am making: Given mass data, you can determine an empirical formula. A substance contains: 2.0g of Ca,1.2g of C, and 4.8g of O. What is the empirical formula of the substance? You know the difference between an empirical and molecular formula. So what should you do? Be certain to try problems of this sort!! I won’t hesitate to ask, and I won’t spend time in class going over these concepts. Chemical Reactions: Mass Relationships in Reactions A.Equations 1. Reactant(s) ---> Product(s) 2. IMPORTANT!!! The number of atoms of each element on both sides of the arrow must be equal. 3. Formulas of reactants and products are fixed! 4. To achieve atomic balance we can adjust only the COEFFICIENTS.
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Page ‹#› A.Equations 4. To achieve atomic balance we can adjust only the COEFFICIENTS. x A + y B ---> z C + w D Chemical Reactions: Mass Relationships in Reactions B. Mechanics 1. Balance atoms of "most complex" substance first. 2. Leave atoms/molecules of elements till later. 3. Examples:
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This note was uploaded on 12/25/2009 for the course CHEM 201 taught by Professor Warren during the Spring '09 term at N.C. State.

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stoichiometry - Chemical Reactions Mass Relationships Some...

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