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3 years ago

Reliable results are results that can be... A: communicated B: evaluated C: duplicated

Chemistry

2 answers:

TEA [102]3 years ago

5 0

I wanna say duplicated...because if you can repeat the same answer twice then its probably right

insens350 [35]3 years ago

4 0

Reliable results are results that can be... A: Communicated

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What is the Ka of a weak acid (HA) if the initial concentration of weak acid is 4.5 x 10-4 M and the pH is 6.87? (pick one)

rewona [7]

Answer:

Ka = $4.04 \times 10^{-11}$

Explanation:

Initial concentration of weak acid = $4.5 \times 10^{-4}\ M$

pH = 6.87

$pH = -log[H^+]$

$[H^+]=10^{-pH}$

$[H^+]=10^{-6.87}=1.35 \times 10^{-7}\ M$

HA dissociated as:

$HA \leftrightharpoons H^+ + A^{-}$

(0.00045 - x) x x

[HA] at equilibrium = (0.00045 - x) M

x = $1.35 \times 10^{-7}\ M$

$Ka = \frac{[H^+][A^{-}]}{[HA]}$

$Ka = \frac{(1.35 \times 10^{-7})^2}{0.00045 - 0.000000135}$

0.000000135 <<< 0.00045

$Therefore, Ka = \frac{(1.35 \times 10^{-7})^2}{0.00045 } = 4.04 \times 10^{-11}$

5 0

2 years ago

What is the current model of atom

leonid [27]

Answer:

The bohr model is the model in use today

7 0

2 years ago

Which of the following statements about electronic configurations of atoms and mononuclear ions, and atomic orbital quantum numb

ruslelena [56]

Answer:

a. The electronic configuration of the hydride anion is 1s2. TRUE

b. The valence electronic configuration of strontium is 4d2. FALSE

c. For a given value of l the number of possible values of ml is 2l + 1. TRUE

d. Cu+ has the same electronic configuration as Ni. TRUE

e. The magnetic quantum number is never larger than the principle quantum number (for a given orbital). TRUE

Explanation:

a. The electronic configuration of the hydride anion is 1s² is true since the hydriden anion is the hdrogen atom which has gained an electron and we will add that electron to the 1s¹ configuration of H.

b. The valence electronic configuration of strontium is 4d2 is false since Sr is an element of period 5 , therefore its valece electrons are in in period five and it has 2 electrons because Sr belongs to group 2.

c. For a given value of l the number of possible values of ml is 2l+1 is true since this number gives the magnetic orientation for the sublevel. Thus for s there is only one orientation, then ml = 2 (0 ) +1 . Por p with l equal to 1 we have three possible orientations : 2(1) + 1 =3. The d and f sublevels have 10 and 14 orientations.

d. Cu⁺ has the the same electronic configuration as Ni is true since Cu, atomic number 29, has one more electron than its neighbor Ni with an atomic number of 28. If we remove one electron from copper we are gong to have the same 28 electrons niquel has in its neutral state.

e. The magnetic quantum number is never larger than the principal quantum number for a given orbital is true since l, the magnetic quantum number can have values up to n-1, the principal quantum number.

4 0

2 years ago

What are centimeters,kilometers,and millimeters

Stells [14]

They are metric units of measurement.

4 0

2 years ago

The density of thorium, which has the FCC structure, is 11.72 g/cm3. The atomic weight of thorium is 232 g/mol. Calculate (a) th

seropon [69]

Answer:

(a) a = 5.08x10⁻⁸ cm

(b) r = 179.6 pm

Explanation:

(a) The lattice parameter "a" can be calculated using the following equation:

$\rho = \frac{(N atoms/cell)*m}{V_{c}*N_{A}}$

where ρ: is the density of Th = 11.72 g/cm³, N° atoms/cell = 4, m: is the atomic weight of Th = 232 g/mol, Vc: is the unit cell volume = a³, and $N_{A}$ : is the Avogadro constant = 6.023x10²³ atoms/mol.