Multiple Choice
Consider the following balanced reaction. What mass (in g) of CO2 can be formed from 288 mg of O2? Assume that there is excess C3H7SH present.
C3H7SH(l) + 6 O2(g) → 3 CO2(g) + SO2(g) + 4 H2O(g)
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3. Chemical Reactions
Stoichiometry
Multiple Choice
Consider the reaction 2HBr(g) → H2(g) + Br2(g). In the first 20.0 s of this reaction, the concentration of HBr dropped from 0.580 M to 0.534 M. Calculate the average rate of the reaction during this time interval in M/s.
A
2.30 x 10^-3 M/s
B
1.15 x 10^-3 M/s
C
1.45 x 10^-3 M/s
D
5.75 x 10^-4 M/s
Verified step by step guidance1
Identify the initial and final concentrations of HBr. The initial concentration [HBr]₀ is 0.580 M, and the final concentration [HBr] is 0.534 M.
Determine the change in concentration of HBr over the time interval. This is calculated as Δ[HBr] = [HBr] - [HBr]₀.
Calculate the time interval over which the reaction occurs. In this case, the time interval Δt is 20.0 seconds.
Use the formula for the average rate of reaction: Rate = -Δ[HBr]/Δt. The negative sign indicates that the concentration of HBr is decreasing.
Substitute the values for Δ[HBr] and Δt into the rate equation to find the average rate of the reaction in M/s.
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