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3 years ago

Why does water have a lopsided shape and act like a chemical magnet?

Chemistry

1 answer:

leva [86]3 years ago

4 0

Answer:

See below

Step-by-step explanation:

(a) Shape

The formula for water is H-O-H.

The central O atom has four electron pairs around it. They try to get as far from each other as possible, so they point toward the corners of a tetrahedron.

Only two of the pairs have a hydrogen atom attached, so water has a bent shape. The H-O-H bond angle is about 104°.

(b) Chemical magnet

The O atom has a greater attraction than H for the shared electrons in the O-H bonds, so the electrons spend more time near the O.

This gives the O atom a partial negative charge (pink in the diagram) and the H atoms a partial positive charge (blue).

The water molecule acts like a chemical magnet because its negative end attracts the positive ends of other molecules, while its positive ends attract the negative ends of other molecules.

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In a chemical reaction, exactly 2 mol of substance A react to produce exactly 3 mol of substance B. 2 A ⟶ 3 B How many molecules

Harman [31]

Answer:

There will be produced 1.71 moles of B which contain 1.03×10²⁴ molecules

Explanation:

The example reaction is:

2A → 3B

2 moles of A produce 3 moles of B

If we have the mass of A, we convert it to moles and then, we make the rule of three: 29.2 g / 25.6g/mol = 1.14 moles

Therefore 2 moles of A produce 3 moles of B

1.14 moles of A will produce (1.14 . 3) / 2 = 1.71 moles of B are produced

Now we can determine, the number of molecules

1 mol has NA molecules (6.02×10²³)

1.71 moles have (1.71 . NA) = 1.03×10²⁴ molecules

4 0

3 years ago

A chemist titrates 130.0mL of a 0.4248 M lidocaine (C14H21NONH) solution with 0.4429 M HBr solution at 25 degree C . Calculate t

jeka57 [31]

Answer:

pH = 3.36

Explanation:

Lidocaine is a weak base to be titrated with the strong acid HBr, therefore at equivalence point we wil have the protonated lidocaine weak conjugate acid of lidocaine which will drive the pH.

Thus to solve the question we will need to calculate the concentration of this weak acid at equivalence point.

Molarity = mol /V ∴ mol = V x M

mol lidocaine = (130 mL/1000 mL/L) x 0.4248 mol/L = 0.0552 mol

The volume of 0.4429 M HBr required to neutralize this 0.0552 mol is

0.0552 mol x (1L / 0.4429mol) = 0.125 L

Total volume at equivalence is initial volume lidocaine + volume HBr added

0 .130 L +0.125 L = 0.255L

and the concentration of protonated lidocaine at the end of the titration will be

0.0552 mol / 0.255 L = 0.22M

Now to calculate the pH we setup our customary ICE table for weak acids for the equilibria:

protonated lidocaine + H₂O ⇆ lidocaine + H₃O⁺

protonated lidocaine lidocaine H₃O⁺

Initial(M) 0.22 0 0

Change -x +x +x

Equilibrium 0.22 - x x x

We know for this equilibrium

Ka = [Lidocaine] [H₃O⁺] / [protonaded Lidocaine] = x² / ( 0.22 - x )

The Ka can be calculated from the given pKb for lidocaine

Kb = antilog( - 7.94 ) = 1.15 x 10⁻⁸

Ka = Kw / Kb = 10⁻¹⁴ / 1.15 x 10⁻⁸ = 8.71 x 10⁻⁷

Since Ka is very small we can make the approximation 0.22 - x ≈ 0.22

and solve for x. The pH will then be the negative log of this value.

8.71 x 10⁻⁷ = x² / 0.22 ⇒ x = √(/ 8.71 X 10⁻⁷ x 0.22) = 4.38 x 10⁻⁴

( Indeed our approximation checks since 4.38 x 10⁻⁴ is just 0.2 % of 0.22 )

pH = - log ( 4.4x 10⁻⁴) = 3.36

3 0

3 years ago

Why do scientist study volcanos!!

agasfer [191]

Answer:

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Explanation:

I HOPE IT HELPED

6 0

3 years ago

Changing the number of ___ gives an atom a neutral charge or causes it to take on a positive or negative charge. (pick on that b

artcher [175]

Answer:

Explanation:

7 0

3 years ago

muriatic acid is the commercial name for hydrochloric acid that can be purchased from hardware stores as a solution that is 30%(

SSSSS [86.1K]

We have 30% (w/w) HCl this means :
100 g solution contains 30 g HCl
?? g solution contains 7.5 g HCl
By cross multiplication:
Mass of solution = $\frac{100 x 7.5 }{30}$ = 25 g solution

5 0

3 years ago