Answer:
The correct answer is due to the difference in pressure inside and outside the bottle.
Explanation:
Liquids have melting and boiling points that depend on pressure and temperature. The pressure inside the bottle is higher than the pressure outside. This causes the melting point to drop, making the liquid freeze at a lower temperature than if it were at atmospheric pressure, and therefore has a lower temperature than it would freeze at atmospheric pressure. When the bottle is uncovered, the liquid becomes an atmospheric pressure, and due to the temperature acquired when the bottle was closed the liquid freezes.
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The answer is 40.
We can solve this by finding out the number of protons, and neutrons. Atomic number of an element means the number of protons in that element. So, the atom has 30 protons if the atomic number is 30.
On the other hand, mass number is the total number of protons and neutrons, but not electrons, because they're too light comparing to the other 2. Therefore, we can simply solve the number of neutrons in the atom by subtracting the number of protons from the mass number. 70 - 30 = 40.
Therfore, the number of neutrons is 40.
Answer:
Enthalpy change for the reaction is -67716 J/mol.
Explanation:
Number of moles of
in 50.0 mL of 0.100 M of 
= Number of moles of HCl in 50.0 mL of 0.100 M of HCl
=
moles
= 0.00500 moles
According to balanced equation, 1 mol of
reacts with 1 mol of HCl to form 1 mol of AgCl.
So, 0.00500 moles of
react with 0.00500 moles of HCl to form 0.00500 moles of AgCl
Total volume of solution = (50.0+50.0) mL = 100.0 mL
So, mass of solution = (
) g = 100 g
Enthalpy change for the reaction = -(heat released during reaction)/(number of moles of AgCl formed)
=
= ![\frac{-100g\times 4.18\frac{J}{g.^{0}\textrm{C}}\times [24.21-23.40]^{0}\textrm{C}}{0.00500mol}](https://tex.z-dn.net/?f=%5Cfrac%7B-100g%5Ctimes%204.18%5Cfrac%7BJ%7D%7Bg.%5E%7B0%7D%5Ctextrm%7BC%7D%7D%5Ctimes%20%5B24.21-23.40%5D%5E%7B0%7D%5Ctextrm%7BC%7D%7D%7B0.00500mol%7D)
= -67716 J/mol
[m = mass, c = specific heat capacity,
= change in temperature and negative sign is included as it is an exothermic reaction]