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Stoichiometry: Calculating Chemical Quantities (Test 1)

Quiz yourself by thinking what should be in each of the black spaces below before clicking on it to display the answer.
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Question
Answer
mole   the SI unit for amount of substance; the quantity of a substance that contains as many molecules or formula units as there are atoms in exactly 12g of carbon-12  
Mole is what kind of word?   "number"  
Mole relates to what?   mass  
What do you use to convert moles to grams or grams to moles?   molar mass  
molar mass   the mass of 1 mol of a substance  
What is the equation for molar mass?   mass/# of moles  
What kind of ratios does the mole concept provide?   mol-to-mol ratios  
Where can you get mol-to-mol ratios?   a) from the subscripts of chemical formulas or b) from the coefficients of balanced equations  
What should you do when balancing equations?   1. Save lone elements for last. 2. Underline as you go.  
When a hydrocarbon or a compound containing only C, H, and O undergoes complete combustion in oxygen, what is formed?   carbon dioxide and water.  
hydrocarbon   a compound containing only carbon and hydrogen  
What is the formula for percent yield?   (actual yield/theoretical yield) times 100%  
What should you do for limiting reactant problems?   1. Write a balanced chemical equation. 2. Determine the theoretical yield for both reactants. 3. The smaller theoretical yield belongs to the limiting reactant; the larger theoretical yield belongs to the excess reactant.  
What should you do to determine percent by mass?   % of an element = (mass of element/total mass of compound) times 100%  
What does a molecular formula show?   the number of atoms of each element in a molecule  
What does an empirical formula show?   the smallest whole number mol-to-mol ratio of elements  
What are two ways to solve empirical/molecular formula problems?   1. Given only percentages by mass, assume 100g of unknown. Multiply the decimal equivalents by 100 to determine the moles. 2. Given percentages by mass and molar mass of the compound, multiply the decimal equivalents to determine the moles.  
In combustion analysis, what does all of the carbon in the unknown get converted to?   carbon dioxide  
In combustion analysis, what does all of the hydrogen in the unknown get converted to?   water  
How do you determine the molecular formula from the empirical formula given the molar mass of the compound?   Divide the molar mass of the compound by the molar mass of the empirical formula. Multiply the subscripts of the empirical formula by the resulting number.  


   






 
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Created by: 2nenogirl