CHEM 24112 Chapter Notes - Chapter 6: Fluorine, Zinc Chloride, Magnesium Oxide
29 Jun 2018
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Homework 6.1: Evidence for a Reaction and Chemical Equations
1. How do we know when a chemical reaction is taking place? Can you think of an example of how
each of the five senses (sight, hearing, taste, touch, smell) might be used in detecting when a chemical
reaction has taken place?
2. Small cuts and abrasions on the skin are frequently cleaned using hydrogen peroxide solution.
What evidence is there that treating a wound with hydrogen peroxide causes a chemical reaction to
take place?
3. For the general equation A + B C + D, which substances are the reactants? Which substances are
the products? What does the arrow signify?
4. Balancing an equation for a reaction ensures that the number of each type of atom is
__________________________________ on both sides of the equation.
5. Why is the physical state of the reactants and products often indicated when writing a chemical
equation? How do we indicate a solid? A liquid? A gaseous substance? A species in aqueous
solution?
6. Pennies in the United States now consist of a zinc disk that is coated with a thin layer of copper. If a
penny is scratched and then soaked in hydrochloric acid, it is possible to dissolve the zinc disk, leaving
only a thin, hollow shell of copper. Write an unbalanced chemical equation to illustrate the reaction of
zinc metal with hydrochloric acid, which produces dissolved zinc chloride and evolves gaseous
hydrogen.
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Document Summary
What does the arrow signify: balancing an equation for a reaction ensures that the number of each type of atom is. A species in aqueous solution: pennies in the united states now consist of a zinc disk that is coated with a thin layer of copper. If a penny is scratched and then soaked in hydrochloric acid, it is possible to dissolve the zinc disk, leaving only a thin, hollow shell of copper. Write the unbalanced equation for this reaction: your family may have a gas grill for outdoor cooking. Gas grills typically use bottled propane gas (c3h8), which burns in air (oxygen) to produce carbon dioxide gas and water vapor. Gas grills should never be used indoors, however, because if the supply of oxygen restricted, the products of this reaction tend to be water vapor and toxic carbon monoxide, instead of nontoxic carbon dioxide.
