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Chem 115 - General Chemistry I

Stoichiometry

Stoichiometry I

Express the following population estimates for the year 2016 in nanomoles of people:

 

1. The United States, 325 million people.

 

2. The world, 7.25 billion people.


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Stoichiometry II

How many moles of sodium ions are there in 1 mole of the following compounds?

 

  1. Na3PO4      
  2. NaNO3    

 

How many iron ions are there in 2.5 moles of each of the following?

 

  1. pyrite, FeS2    
  2. magnetite, Fe3O4  


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Stoichiometry III

Calculate the molar masses of the following common flavors in food:

1. vanillin, C8H8O3     

2. oil of cloves, C10H12O2  


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    • Stoichiometry IV

    Epsom salts are a hydrate of magnesium sulfate, MgSO4×7H2O. For a beneficial bath, pour 2 cups into a tubful of warm water. There are many benefits of Epsom salt baths. Soaking in a bath of Epsom salt can relax your muscles, reduce inflammation, minimize pain, fade bruising, aid digestion, and detoxify your body. It can also lower your blood pressure, improve your concentration, and help you sleep.

     

    Epsom salt baths naturally boost your mood. Magnesium aids in the conversion of tryptophan, to the mood-enhancing neurotransmitter serotonin. Stress can cause a deficiency of magnesium in your blood, but soaking in an Epsom salt bath allows magnesium to be absorbed through the skin.


    What is the molar mass of Epsom salts?


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    • Stoichiometry V

    What is the volume of 1.00 mol of benzene (C6H6) at 20°C? The density of benzene is 0.879 g/mL.


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    • Stoichiometry VI

    Aspirin (C9H8O4), acetaminophen (C8H9NO2) and naproxen sodium (C14H13O3Na) are common pain relievers available in tablets containing 200.0 mg of the active ingredient. How many molecules of the active ingredient are present in each tablet?


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    • Stoichiometry VII

    Diamond is a crystalline form of carbon. The famous Hope Diamond at weighs 45.52 carats.  How many carbon atoms are in the diamond? (1 carat = 200 mg, exact)


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    • Stoichiometry VIII

    Balance the following reactions that occur among volcanic gases:
    • SO2(g)  +  O2(g) ➞     SO3(g)
    • H2S(g)  +  O2(g) ➞      SO2(g)    +   H2O(g)


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    Stoichiometry IX

    Drierite is the brand name of a variety of desiccants made from anhydrous calcium sulfate. Each empirical unit of calcium sulfate can absorb two molecules of water. Drierite contains a trace of a color indicator that shows when it cannot absorb any more water. However, one can regenerate anhydrous calcium by heating it in a drying oven and driving off the water. What mass of water is released when 2.00 grams of CaSO4×2H2O are heated in a drying oven.

    CaSO4×2H2O(s)      CaSO4(s)      +     2 H2O(g)


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    • Stoichiometry X

    A 0.86 mole sample of benzene (C6H6) undergoes complete combustion in oxygen. Write the balanced chemical equation. How many moles of water and carbon dioxide will be produced? How many moles of oxygen gas were required?

    ____ C6H6     +     ____ O2      ➞    ____ CO2    +  ____ H2O 


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    • Stoichiometry XI

    In the early 20th century, Londoners suffered from severe air pollution caused by burning high-sulfur coal. The sulfur dioxide that was emitted into the air mixed with London fog, forming sulfuric acid. For every gram (1.00 g) of sulfur that was burned, how many grams of sulfuric acid could have formed?

    S(s)       +       O2(g)       ➞      SO2(g)
    SO2(g)    +    H2O(g)     ➞     H2SO4(aq)


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