This is a difficult task because zinc is much more active than copper and could hardly be passivated. ... The sur- face immediately turns white (the color of copper(I) iodide) and the yellow-brown color of iodine quickly fades. Rinse the coin with water, brighten it with polish and cloth and begin the whole process again.N
Answer:
19
Explanation:
1240.64/64
This is a simple division that can easily be evaluated using any form of calculator.
Here, the main challenge is in expressing the answer in the proper number of significant figure.
The approach here is to express the answer to the which is least precise. This is usually the number with the lower significant values.
Here, 64 has two significant figures and it is of a lower rank. Our answer should be expressed this way:
= 19.385 = 19
Answer:
D
Explanation:
Of the four given equations, we want to determine which will most likely have a positive Δ<em>S</em>.
A positive Δ<em>S</em> indicates an increase in entropy. Recall that entropy can be described as the "randomness" of a substance. Therefore, gases have the highest entropy, followed by liquids and solids.
Examining each answer choice:
- A is unlikely to have a positive Δ<em>S</em>, as gases are being converted into solids. As a result, entropy is lowered.
- B is likewise unlikely to have a positive Δ<em>S</em>. Multiple moles of gases are being converted into solution and another gas, leading to a decrease in "randomness."
- While all species involved in C are gases, we can see that two moles of gases react to form only one. Because the amount of gases decrease as the reaction proceeds, the amount of "randomness" likewise decreases, indicating a decrease in entropy.
- D is the best answer. One mole of gas reacts to form three moles of gas, thereby increasing "randomness" and hence increasea entropy.
Answer:
The correct answer is option C.
Explanation:
Half life for second order kinetics is given by:
= half life = 15.4 s
k = rate constant =?
= initial concentration = 0.67 M
is the rate constant for this reaction.