Chemistry, 23.06.2021 05:00, dashawn3rd55

For a particular chemical reaction the rate (g/hr) at which one of the reactants changes is proportional to the amount of that reactant present. If y represents the amount of that reactant at time t, StartFraction dy Over dt EndFraction equals minus0.7y. If there were 70 grams of the reactant when the process started (tequals 0), how many grams will remain after 4 hours?

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answered: 23kaevans

Amount of reactant after four hours = 4,26 grams

Explanation:

Suppose y denotes the amount of reactant at the time (t)

The given function:

$\dfrac{dy}{dt} = -0.7 y$

$\dfrac{dy}{y} = -0.7 dt$

Taking integral on both sides

㏑(y) = -0.7t + c¹

$e^{In(y)}= e^{-0.7t + c^1}$

$y(t) = Ce ^{-0.7t}$

At t = 0 ; y (t) = 70

∴

$70 = Ce^{-0.7(0)}$

C = 70

As such; $\mathtt{y(t) = 70 e^{-0.7*t}}$

After four hours, the amount of the reactant is:

$\mathtt{y(t) = 70 e^{-0.7*4}}$

$\mathtt{y(t) = 70 e^{-2.8}}$

$\mathtt{y(t) = 4.26}$

Amount of reactant after four hours = 4,26 grams

answered: Guest

Answer: abeexplanation:

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.

answered: Guest

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃ → 3 nicl₂ + 2 albarium and copper bromideba + cubr → no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn → znso₄ + na

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For a particular chemical reaction the rate (g/hr) at which one of the reactants changes is proport...