H 2 I 2 2 HI 1 2 1 2 162 10 3 722 10 5 00450 00095 31107 1555 ln 31107 ln 1555

H 2 i 2 2 hi 1 2 1 2 162 10 3 722 10 5 00450 00095

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H 2 + I 2 2 HI 𝑅𝑎?𝑒 1 𝑅𝑎?𝑒 2 = ?[????] 1 𝑚 ?[????] 2 𝑚 1.62 × 10 −3 7.22 × 10 −5 = ( 0.0450 0.0095 ) 𝑚 3.1107 = 1.555 𝑚 ln 3.1107 = ? ln 1.555 ? = 1.999 ≈ 2 2 nd order Acids donate H + in water: HSO 4 - + H 2 O SO 4 2- + H 3 O + Ca(NO 3 ) 2 (aq) + Na 2 CO 3 (aq) CaCO 3 (s) + 2 NaNO 3 (aq)
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STEM-Dawgs Workshops Practice Exam 3 KEY CHEM 142B Solutions are available on Canvas . 6. Using your balanced reaction and the data provided in 5., calculate the mass of precipitate that forms when the solutions are mixed together. 7. Using your balanced equation and the data provided in 5., calculate the final concentration of carbonate in the solution after the reaction. 8. The part of the Kinetic Molecular Theory that best explains the relationship between the volume and pressure of a gas is: a) Volume of individual gas particles is zero b) Kinetic energy of gas particles is proportional to temperature c) Gas particles travel in straight lines d) Gas particles are neither attracted nor repelled by other gas particles e) Gas particles exert pressure by colliding with the walls of the container 9. A student pipettes 5.00 mL of a 0.225 M NaCl solution into a 100.0 mL volumetric flask. What is the concentration of the diluted NaCl solution? 10. A sample of an unknown compound is vaporized at 100 o C. The gas produced has a volume of 1655 mL at a pressure of 1.00 atm with a mass of 2.49 grams. Assuming the gas behaves as an ideal gas under these conditions, which of the following substances might be the identity of the gas? a) C 2 H 6 O b) C 2 H 4 O 2 c) CH 2 O d) C 3 H 6 O 2 Find the starting moles of both species: Na 2 CO 3 : 0.525 ? × 0.300 ? = 0.158 ?𝑜?𝑒? and Ca(NO 3 ) 2 : 0.225 ? × 0.125 ? = 0.0281 ?𝑜?𝑒? The net ionic reaction tells us that there is a 1:1 ratio of Ca 2+ to CO 3 2- , therefore, we can just compare the starting moles to figure out the limiting reactant. Ca 2+ will be used up first and makes 0.0281 moles of CaCO 3 . Now find the mass of precipitate: 0.0281?𝑜?𝑒? × 100.08 𝑔 ?𝑜?𝑒 = ?. 𝟖? 𝒈 We know that 0.0281 moles of CO 3 2- reacted. Find the remaining: 0.158 moles 0.0281 moles = 0.130 moles remain. Divide this by the total volume, which is 0.525 L + 0.225 L = 0.750 L
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  • Chemical reaction, Rate equation

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