It can take 49 days, I could be wrong. What do you mean in this question?
Answer:
kJ/mol
Explanation: <u>Enthalpy</u> <u>Change</u> is the amount of energy in a reaction - absorption or release - at a constant pressure. So, <u>Standard</u> <u>Enthalpy</u> <u>of</u> <u>Formation</u> is how much energy is necessary to form a substance.
The standard enthalpy of formation of HCl is calculated as:

→ 
Standard Enthalpy of formation for the other compounds are:
Calcium Hydroxide:
-1002.82 kJ/mol
Calcium chloride:
-795.8 kJ/mol
Water:
-285.83 kJ/mol
Enthalpy is given per mol, which means we have to multiply by the mols in the balanced equation.
Calculating:
![-17.2=[-795.8+2(285.85)]-[-1002.82+2\Delta H]](https://tex.z-dn.net/?f=-17.2%3D%5B-795.8%2B2%28285.85%29%5D-%5B-1002.82%2B2%5CDelta%20H%5D)



So, the standard enthalpy of formation of HCl is -173.72 kJ/mol
Answer:
The diameter of the hydrogen 
Explanation:
From the given information:
Using the concept of Bohr's Model, the equation for the angular momentum can be expressed as:

Where the generic expression for angular momentum is:
L = mvr.
replacing the value of L into the previous equation, we have:

----- (1)
The electron in the hydrogen atom posses an electrostatic force which gives a centripetal force.
----- (2)
replacing the value of v in equation (1) into (2), and taking r as the subject of the formula, we have:



For ground-state n = 1






Therefore, the diameter of hydrogen d = 2r


Actually Rb or Rubidium in zero state has the following
electron configuration:
<span>1s22s2</span><span>2p6</span><span>3s2</span><span>3p63d10</span><span>4s2</span><span>4p65s1</span>
However we can see that the ion has a 1 positive charge,
which means that it lacks 1 electron, therefore the answer from the choices is:
<span>d.
rb+: 1s22s22p63s23p64s23d104p6</span>
Answer:
91.26 g
Explanation:
Given data:
Mass of PF₃ = 180 g
Mass of F₂ required = ?
Solution:
Chemical equation:
P₄ + 6F₂ → 4PF₃
Moles of PF₃:
Number of moles = mass/ molar mass
Number of moles = 180 g/ 88 g/mol
Number of moles = 2.05 mol
Now we will compare the moles of PF₃ with F₂.
PF₃ : F₂
4 : 6
2.05 : 6/4×2.05 = 3.075
Mass of F₂:
Mass of F₂ = moles × molar mass
Mass of F₂ = 3.075 mol × 38 g/mol
Mass of F₂ = 116.85 g
If reaction yield is 78.1%:
116.85 /100 ×78.1 = 91.26 g