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# 112 mhr chemistry 12 solutions manual 978 0 07 106042

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112 MHR ● Chemistry 12 Solutions Manual 978 -0-07-106042-4 3. For the reaction shown below, the average rate of formation of CO 2 (g) is 5.50 × 10 4 mol/s. Br 2 (aq) + HCOOH(aq) 2Br (aq) + 2H + (aq) + CO 2 (g) a. What amount in moles of CO 2 (g) is formed in 5.00 min? What Is Required? You need to calculate the amount in moles of CO 2 (g) produced in 5.00 min. What Is Given? You know the balanced chemical equation for the reaction. You know the average rate of formation of CO 2 (g): rate = 5.50 × 10 4 mol/s You know the time elapsed: t = 5.00 min Plan Your Strategy Act on Your Strategy Convert the units for time elapsed, t , from minutes to seconds. 5.00 min 5.00 min t g32 g32 60 s min g117 300 s g32 Use the expression concentration n t t g39 g32 g117 g39 to calculate the amount in moles, n , of CO 2 (g). 2 CO –4 concentration 5.50 10 mol 1 s n t t g39 g32 g117 g39 g117 g32 300 s g117 0.165 mol g32 b. How does this compare with the amount of Br 2 (aq) that reacts in the same time? What Is Required? You need to compare the amount of CO 2 (g) produced to the amount of Br 2 (aq) consumed. What Is Given? You know the amount of CO 2 (g) produced. You know the balanced chemical equation. Plan Your Strategy Act on Your Strategy The rate of consumption of reactants is in proportion to the mole ratio given in the balanced equation. Determine the mole ratio from the balanced equation. 2 2 Br CO 1 1 n n g32

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Unit 3 Part B ● MHR 113 Determine the rate at which Br 2 (aq) reacts. 2 2 [Br ] [CO ] t t g39 g39 g32 g39 g39 Br 2 (aq) will be consumed at the same rate as CO 2 is produced. Therefore, 0.165 mol of Br 2 (aq) reacts in this same time interval. Check Your Solution The answer has the correct number of significant digits. The equation shows a 1:1 mol ratio between Br 2 (aq) and CO 2 (g). The answer is reasonable.
114 MHR ● Chemistry 12 Solutions Manual 978 -0-07-106042-4 4. The concentration of a reactant is 4.0 × 10 2 mol/L at t = 2.0 min. If the average rate of consumption of the reactant from t = 1.5 min to t = 2.0 min was 0.045 mol/ L•s , what was the concentration of this reactant at t = 1.5 min? What Is Required? You need to determine the concentration of a reactant after 1.5 minutes have elapsed in the reaction. What Is Given? You know the average rate of reaction: rate = 0.045 mol/ L•s You know the final concentration: c final = 4.0 × 10 2 mol/L You know the initial time: t initial = 1.5 min You know the final time: t final = 2.0 min Plan Your Strategy Act on Your Strategy Convert the units for t initial and t final from minutes to seconds. initial 1.5 min 1.5 min t g32 g32 60 s min g117 90 s g32 final 2.0 min 2.0 min t g32 g32 60 s min g117 120 s g32 Determine the time elapsed, ∆ t . final initial 120 s 90 s 30 s t t t g39 g32 g16 g32 g16 g32 Use the formula concentration average rate t g39 g32 g16 g39 to calculate the initial concentration, c initial . The rate is negative because the amount of reactant is decreasing.
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• Winter '18
• Mole, Chemical reaction, Molar concentration

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