The easiest way to approximate ph level is through the ph paper measurement system because using pH paper would be best for doing a quick measurement in the field. It does not essentially need to be calibrated or standardized and the papers make available an instant estimate.
Answer:
The standard enthalpy of formation of methane is -67.2 kJ/mol.
Explanation:
...[1]
...[2]
...[3]
Since, the bond formation is taking place energy will release that id reaction will be an exothermic reaction
![\Delta H^o_{3,rxn} =4\times (-414 kJ/mol)=-1656 kJ/mol](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7B3%2Crxn%7D%20%3D4%5Ctimes%20%28-414%20kJ%2Fmol%29%3D-1656%20kJ%2Fmol)
...[4]
Using Hess's law:
[4] = [1] + [2] + [3]
![\Delta H^o_{4,rxn} =\Delta H^o_{1,rxn} +\Delta H^o_{2,rxn} +\Delta H^o_{3,rxn}](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7B4%2Crxn%7D%20%3D%5CDelta%20H%5Eo_%7B1%2Crxn%7D%20%2B%5CDelta%20H%5Eo_%7B2%2Crxn%7D%20%2B%5CDelta%20H%5Eo_%7B3%2Crxn%7D%20)
![=716 kJ/mol+872.8 kJ/mol +(-1656 kJ/mol)=-67.2 kJ/mol](https://tex.z-dn.net/?f=%3D716%20kJ%2Fmol%2B872.8%20kJ%2Fmol%20%2B%28-1656%20kJ%2Fmol%29%3D-67.2%20kJ%2Fmol)
The standard enthalpy of formation of methane is -67.2 kJ/mol.
Answer:
14
Explanation:
Silicon has atomic number 14, so its nucleus contains 14 protons
no. of protons + no. of neutrons = atomic mass number
p + n = A
14 + n = 28
n = 28 - 14 = 14
An atom of Si-28 contains 14 neutrons.
Answer:
30%
Explanation:
The relative humidity is the water-vapor content of the air relative to its content at saturation. Saturated air, for example, has a relative humidity of 100 percent, and near the Earth, the relative humidity very rarely falls below 30 percent.