Answer:
8 valence electrons
Explanation:
There are 4 valence electrons in carbon because it is in group 4A of the periodic table. There is 1 valence electron per hydrogen based on its position on the periodic table, but CH4 has 4 hydrogens in it. So 1 times 4 is 4. Add the 4 valence electrons from carbon with the 4 electrons from H4 to get 8.
Solids, liquids, gases, and plasma are all matter. When all atoms that make up a substance are the same, then that substance is an element. Elements made of only one kind of atom. Because of this, elements are called "pure" substances.
hope this helps :)
Answer:
Magnets can be used in space. ... One class of magnets, called electromagnets, does need electricity to work.
Explanation:
Answer: The entropy change of the surroundings will be -17.7 J/K mol.
Explanation: The enthalpy of vapourization for 1 mole of acetone is 31.3 kJ/mol
Amount of Acetone given = 10.8 g
Number of moles is calculated by using the formula:
![\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}](https://tex.z-dn.net/?f=%5Ctext%7BNumber%20of%20moles%7D%3D%5Cfrac%7B%5Ctext%7BGiven%20mass%7D%7D%7B%5Ctext%7BMolar%20mass%7D%7D)
Molar mass of acetone = 58 g/mol
Number of moles = ![\frac{10.8}{58}=0.1862moles](https://tex.z-dn.net/?f=%5Cfrac%7B10.8%7D%7B58%7D%3D0.1862moles)
If 1 mole of acetone has 32.3 kJ/mol of enthalpy, then
0.1862 moles will have = ![\frac{32.3}{1}\times 0.1862=5.828kJ/mol](https://tex.z-dn.net/?f=%5Cfrac%7B32.3%7D%7B1%7D%5Ctimes%200.1862%3D5.828kJ%2Fmol)
To calculate the entropy change for the system, we use the formula:
![\Delta S_{sys}=\frac{\Delta H_{vap}}{T(\text{ in K)}}](https://tex.z-dn.net/?f=%5CDelta%20S_%7Bsys%7D%3D%5Cfrac%7B%5CDelta%20H_%7Bvap%7D%7D%7BT%28%5Ctext%7B%20in%20K%29%7D%7D)
Temperature = 56.2°C = (273 + 56.2)K = 329.2K
Putting values in above equation, we get
(Conversion Factor: 1 kJ = 1000J)
At Boiling point, the liquid phase and gaseous phase of acetone are in equilibrium. Hence,
![\Delta S_{system}+\Delta S_{surrounding}=0](https://tex.z-dn.net/?f=%5CDelta%20S_%7Bsystem%7D%2B%5CDelta%20S_%7Bsurrounding%7D%3D0)
![\Delta S_{surrouding}=-\Delta S_{system}=-17.7J/Kmol](https://tex.z-dn.net/?f=%5CDelta%20S_%7Bsurrouding%7D%3D-%5CDelta%20S_%7Bsystem%7D%3D-17.7J%2FKmol)