Answer:
2.25g of NaF are needed to prepare the buffer of pH = 3.2
Explanation:
The mixture of a weak acid (HF) with its conjugate base (NaF), produce a buffer. To find the pH of a buffer we must use H-H equation:
pH = pKa + log [A-] / [HA]
<em>Where pH is the pH of the buffer that you want = 3.2, pKa is the pKa of HF = 3.17, and [] could be taken as the moles of A-, the conjugate base (NaF) and the weak acid, HA, (HF). </em>
The moles of HF are:
500mL = 0.500L * (0.100mol/L) = 0.0500 moles HF
Replacing:
3.2 = 3.17 + log [A-] / [0.0500moles]
0.03 = log [A-] / [0.0500moles]
1.017152 = [A-] / [0.0500moles]
[A-] = 0.0500mol * 1.017152
[A-] = 0.0536 moles NaF
The mass could be obtained using the molar mass of NaF (41.99g/mol):
0.0536 moles NaF * (41.99g/mol) =
<h3>2.25g of NaF are needed to prepare the buffer of pH = 3.2</h3>
Answer: energy needed to remove an electron from an atom or ion in the gas phase. Explanation: That is the very definition of ionization energy: ionization energy is the energy needed to remove (get appart) an electron from a neutral atom or ion in gas phase.Jun 19, 2016
Answer:
I won’t do it in paragraph form cuz it will look very choppy but here you go:
Weathering is when the weather itself changes something, like when a metal bike gets rusty after sitting outside for a long time, or when a plant grows out of concrete.
Erosion is when something gets eroded away at. Like when something has water or wind is flowing against it so much that it changes shape. This is how canyons are made.
Deposition is when a gas turns into a solid, removing energy and skipping the liquid step (frost forming on car window)
Answer: The correct answer is option B.
Explanation: There are 7 elements in group VIII-A. They are Helium (He), Neon(Ne), Argon(Ar), Krypton (Kr), Xenon (Xe), Radon (Rn) and Ununoctium (Uuo). They are considered as a part of group 18.
Metals are shown in purple color in the periodic table. Metalloids as blue color and Non-metals are shown in green color.
Group VIII-A elements have fully filled orbitals and hence are most stable amongst all the elements in the periodic table. They are considered as least reactive elements and as they are categorized as non-metals. So, they are the least reactive non-metals.
Therefore, the correct option is B.
