# 2 reaction b is a combustion reaction a how can you

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2. Reaction B is a combustion reaction. a. How can you tell that it is a combustion reaction, based on the chemical equation? © M i c h i g a n V i r t u a l U n i v e r s i t y P a g e 1 | 5
UNIT 9 STOICHIOMETRY / 9.3 LIMITING REACTANT AND PERCENT YIELD
b. In this lesson, we used the number of moles or the masses of the reactants in our calculations to determine which reactant was the limiting reactant.The demonstrator did not base her experiment on the number of moles or on the masses of the reactants for the different trials. Since she didn’t use number of moles or the masses of the reactants, what units did she use?
c. Using what you know about balanced chemical equations, explain why she could use these units.
Section 2: Analyzing the Lab Demonstration We will now analyze the experiments that the demonstration performed using masses of the reactants and one of the products for the following chemical equation: 2 C 2 H 2 ( g ) + 5 O 2 ( g ) → 4 CO 2 ( g ) + 2 H 2 O ( l ). She used the flaming splint test on three different test tubes, each of which contained a different amounts of acetylene gas. The masses of the reactants for the three trials are listed in the following table. Watch the video “ Acetylene Gas Demonstration ” again and take notes in the far right colum of the table for each trial. Include information about how loud the “pop” was and how sooty or clean the test tube became. Trial # Mass of C 2 H 2 Mass of O 2 Mass of CO 2 Description of Reaction: How loud was the “pop”? How sooty/clean did the test tube become? 1 5.82 x 10 -2 g 2.24 x 10 -2 g 2.01 x 10 -2 g Lots of black soot 2 4.10 x 10 -2 g 1.17 x 10 -1 g 1.077 x 10 -1 g Little bit of black soot was © M i c h i g a n V i r t u a l U n i v e r s i t y P a g e 2 | 5