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SIZIF [17.4K]
4 years ago
10

What percentage of a radioactive species would be found as daughter material after seven half–lives?

Chemistry
1 answer:
irinina [24]4 years ago
6 0
0.78  is what the verified answer says 
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1) The heat of combustion for the gases hydrogen, methane and ethane are −285.8, −890.4 and −1559.9 kJ/mol respectively at 298K.
Morgarella [4.7K]

Answer:

The enthalpy of the reaction is 64.9 kJ/mol.

Explanation:

H_2 + \frac{1}{2}O_2\rightarrow H_2O,\Delta H_1 =-285.8 kJ..[1]

CH_4 + 2O_2\rightarrow CO_2 + 2H_2O,\Delta H_2 =-890.4 kJ..[2]

C_2H_6 + \frac{7}{2}O_2\rightarrow 2CO_2 + 3H_2O,\Delta H_3= -1559.9 kJ..[3]

2CH_4(g)\rightarrow C_2H_6(g) + H_2(g),\Delta H_4=?..[4]

2 × [2] - [1]- [3] = [4]  (Using Hess's law)

\Delta H_4=2\times \Delta H_2 -\Delta H_1 -\Delta H_3

\Delta H_4=2\times (-890.4 kJ)-(-285.8 kJ) -(-1559.9 kJ)

\Delta H_4=64.9 kJ/mol

The enthalpy of the reaction is 64.9 kJ/mol.

3 0
3 years ago
Can someone tell me the answer ?
ludmilkaskok [199]
The Aufbau principle states that, hypothetically, electrons orbiting one or more atoms fill the lowest available energy levels before filling higher levels (e.g., 1s before 2s). In this way, the electrons of an atom, molecule, or ion harmonize into the most stable electron configuration possible.
7 0
3 years ago
10 points!
Alik [6]

I believe that it is all of the above.

"A Scientific Hypothesis Must Be "Falsifiable". A scientific hypothesis must be testable, but there is a much stronger requirement that a testable hypothesis must meet before it can really be considered scientific."

I hope this helped, have a nice day!

6 0
3 years ago
Read 2 more answers
What does a most-favored-nation (MFN) status mean?
MatroZZZ [7]

Most Favored Nation status is an economic position in which a country enjoys the best trade terms given by its trading partner. That means it receives the lowest tariffs, the fewest trade barriers, and the highest import quotas (or none at all).

I got this from google, hope it helps! :)

7 0
3 years ago
Read 2 more answers
Explain why energy sources do not have 100% efficiency. Why do you think some have lower efficiencies?
bearhunter [10]

Answer:

Energy sources do not have 100% efficiency because <em>the processes of energy conversion to usable forms involves energy losses. </em>

Some have lower efficiencies due to; <u>energy losses in form of heat</u> during conversion, <u>poor technology applied during conversion</u> of energy and<u> lack of desire equipment</u> to use in the energy conversion system.

Explanation:

The desired form of energy for use is derived from conversion of energy from the source using an energy converter into another form which is usable. The efficiency of the energy converter is calculated as;

л = output energy/input energy

The efficiency of energy is limited to the cost of equipment required for conversion from energy source by the energy converter to a form which is usable. Additionally, because energy sources are scarce, the technology to use in energy  conversion is a factor affecting energy efficiency in that high efficiency will require advanced technology with better equipment leading higher costs of that energy form. when heat losses are involved during energy conversion, efficiency lowers, thus its better if such losses are used as energy input in another system.

5 0
3 years ago
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