A chemist wishes to determine the rate of reaction of zinc with hydrochloric acid. The equation for the reaction is:
Zn(s) + 2HCl(aq) ---> H2(g) + ZnCl2(aq)
A piece of zinc is dropped into 1.00 L of 0.100 M HCl and the following data were obtained:
Time/Mass of Zinc
0 s/0.016 g
4 s/0.014 g
8 s/0.012 g
12 s/0.010 g
16 s/0.008 g
20 s/0.006 g
Calculate the Rate of Reaction in moles of Zn consumed per second.
To calculate the rate of reaction in moles of Zn consumed per second, we need to determine the change in the amount of Zn over time. The decrease in mass of Zn is equivalent to the amount of Zn consumed in the reaction.
Given the data provided, we can use the change in mass of Zn and the corresponding time intervals to calculate the rate of reaction.
First, let's calculate the change in mass of Zn for each time interval:
For the interval from 0 s to 4 s:
Change in mass = 0.016 g - 0.014 g = 0.002 g
For the interval from 4 s to 8 s:
Change in mass = 0.014 g - 0.012 g = 0.002 g
For the interval from 8 s to 12 s:
Change in mass = 0.012 g - 0.010 g = 0.002 g
For the interval from 12 s to 16 s:
Change in mass = 0.010 g - 0.008 g = 0.002 g
For the interval from 16 s to 20 s:
Change in mass = 0.008 g - 0.006 g = 0.002 g
Now, let's calculate the rate of reaction for each time interval by dividing the change in mass by the corresponding time interval:
For the interval from 0 s to 4 s:
Rate of reaction = (0.002 g) / (4 s - 0 s) = 0.0005 g/s
For the interval from 4 s to 8 s:
Rate of reaction = (0.002 g) / (8 s - 4 s) = 0.0005 g/s
For the interval from 8 s to 12 s:
Rate of reaction = (0.002 g) / (12 s - 8 s) = 0.0005 g/s
For the interval from 12 s to 16 s:
Rate of reaction = (0.002 g) / (16 s - 12 s) = 0.0005 g/s
For the interval from 16 s to 20 s:
Rate of reaction = (0.002 g) / (20 s - 16 s) = 0.0005 g/s
Since the stoichiometry of the reaction is 1:1 for Zn and H2 (1 mole of Zn reacts to form 1 mole of H2), the moles of Zn consumed per second is equal to the rate of reaction in grams per second divided by the molar mass of Zn (65.38 g/mol):
Rate of reaction (moles of Zn/s) = (0.0005 g/s) / (65.38 g/mol) ≈ 7.64 x 10^-6 moles/s
Therefore, the rate of reaction in moles of Zn consumed per second is approximately 7.64 x 10^-6 moles/s.