How many liters of a 0.225 M solution of KI are needed to contain 0.935 moles of KI?
1 answer:
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Answer:
The answer is 80,1 °C
Explanation:
Let´s start from the mass of the sample and the heat capacities:
First of all, we must calculate an average heat capacity. That's because we have a mixture and it is unknown the heat capacity of the whole sample.
The way we should do this calculation is as follows:
(1)
For example, the mass fraction of Fe is simply:
(2)
If you combine the equations (1) and (2) you have:
(3)
Once calculated the average heat capacity we can solve the problem taking into account the corresponding equation:
(4)
Remember that:
<em>Q:</em> Heat gained or lost
<em>m</em>: Mass of the sample you want to analize
: The value obtained in equation (3)
: Final temperature of the sample
: Initial temperature of the sample
Now we must replace the problem data in equation (4)
Take into account:
- Heat gained in a system have a positive value
- Heat lost in a system have a negative value
- In this problem the sample loses 200 J, for this reason
- The mass of the whole sample is: 10g of Fe + 10g of Ti = 20g of sample
- The temperatures must be in absolute units of temperature (these are: rankine or kelvin)
- The initial temperature of the system is 100°C or 373K
Now we are ready to use equation (4):
(5)
It is clear that the unknown in equation (5) is
The next step is to calculate . Don't forget the signs; these are important.
Key concept: <u>Since the system is loosing heat, the final temperature of the system ( ) should be lower than the initial temperature (
)</u>
Answer:- selenium, Se.
Explanations:- When an element gain electrons then it becomes negatively charged means it forms it's anion. Total electrons of the anion are the sum of electrons and the charge of the anion. In our problem, the element is q and it forms ion. The Total electrons for the anion
= electrons of q + 2
As per the given info, there are 36 electrons in ion.
So, 36 = electrons of q + 2
electrons of q = 36 - 2
electrons of q = 34
q, the neutral atom has 34 electrons means it's atomic number is 34. If we check out the periodic table then the element with atomic number 34 is Selenium, Se.