Answer:
An area around a molecule that describes a region of space where the electrons that are shared between bonded atoms can reside
Explanation:
A molecular orbital is an area around a molecule that describes a region of space where the electrons that are shared between bonded atoms can reside.
Molecular orbitals are formed by linear combination of atomic orbitals of about the same energy. The number of atomic orbitals that are combined to give molecular orbitals is the same as the number of molecular orbitals formed. The build up of electrons in molecular orbitals also follow the Aufbau principle, Hund's rule and Pauli exclusion principle.
Answer:
6.574 g NaF into 300ml (0.25M HF) => Bfr with pH ~3.5
Explanation:
For buffer solution to have a pH-value of 3.5 the hydronium ion concentration [H⁺] must be 3.16 x 10⁻⁴M ( => [H⁺] = 10^-pH = 10⁻³°⁵ =3.16 x 10⁻⁴M).
Addition of NaF to 300ml of 0.25M HF gives a buffer solution. To determine mass of NaF needed use common ion analysis for HF/NaF and calculate molarity of NaF, then moles in 300ml the x formula wt => mass needed for 3.5 pH.
HF ⇄ H⁺ + F⁻; Ka = 6.6 x 10⁻⁴
Ka = [H⁺][F⁻]/[HF] = 6.6 x 10⁻⁴ = (3.16 x 10⁻⁴)[F⁻]/0.25 => [F⁻] = (6.6 x 10⁻⁴)(0.25)/(3.16x10⁻⁴) = 5.218M in F⁻ needed ( = NaF needed).
For the 300ml buffer solution, moles of NaF needed = Molarity x Volume(L)
= (5.218M)(0.300L) = 0.157 mole NaF needed x 42 g/mole = 6.574 g NaF needed.
Check using the Henderson - Hasselbalch Equation...
pH = pKa + log ([Base]/[Acid]); pKa (HF) = 3.18
Molarity of NaF = (6.572g/42g/mole)/(0.300 L soln) = 0.572M in NaF = 0.572M in F⁻.
pH = 3.18 + log ([0.572]/[0.25]) ≅ 3.5.
One can also back calculate through the Henderson -Hasselbalch Equation to determine base concentration, moles NaF then grams NaF.
C: One plate is going underneath the other plate and sinking into the soft rock below.
Explanation:
Where plates are moving towards each other they are said to converging, and are called convergent margins.
The lithosphere is broken into series of slabs called plates. The plates moves on the weak and relatively soft asthenosphere below.
Plates have different motion. At some places, they move apart and they are said to be divergent.
When plates moves towards each other, they are convergent. At a convergent margin, a plate collides with another thereby causing the denser plate usually the oceanic plate to subduct into the asthenosphere. In some other cases, the plates can collide and build upward.
Learn more:
Lithosphere brainly.com/question/9582362
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Answer:
cutting, bending, dissolving, freezing, and boiling
Explanation:
A physical change is a change in one or more physical properties of matter without any change in chemical properties. In other words, matter doesn't change into a different substance in a physical change. Examples of physical change include but are not limited to, from solid to liquid or from liquid to gas are also physical changes.
