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BabaBlast [244]
3 years ago
12

Suppose hydrogen sulfide is added to a solution that is 0.10 M in Cu2+, Pb2+, and Ni2+ such that the concentration of H2S is 0.1

0 M. When the pH of the solution is adjusted to 1.00, a precipitate forms. What is the composition of the precipitate? H2S(aq) + 2H2O(l) 2H3O+(aq) + S2–(aq); Kc = 1.1 × 10–20 Salt Ksp CuS 6.0 × 10–36 PbS 2.5 × 10–27 NiS 3.0 × 10–19
A. NiS only
B. CuS, PbS, and NiS
C. CuS and PbS
D. CuS only
E. PbS and NiS
Chemistry
1 answer:
Stels [109]3 years ago
7 0

Answer:

C. CuS and PbS  

Explanation:

1. Calculate [H₃O⁺]

pH = 1.00  

\rm [H_{3}O^{+}] = 10^{-pH} = \text{0.100 mol/L}

2. Calculate the concentration of S²⁻

H₂S + 2H₂O ⇌ S²⁻ + 2H₃O⁺; Kc =  1.1 × 10⁻²⁰

K_{\text{c}} = \dfrac{\text{[S$^{2-}$][H$_{3}$O$^{+}$]}^{2}}{\text{[H$_{2}$S ]}}\\\\\text{[S$^{2-}$]} = \dfrac{K_{\text{a}}\text{[H$_{2}$S]}}{\text{[H}_{3}\text{O}^{+}]^{2}}= \dfrac{1.1 \times 10^{-20} \times 0.10}{0.100^{2}} = 1.1 \times 10^{-19}

3. Calculate Qsp for the sulfides

(a) CuS

CuS ⇌ Cu²⁺ + S²⁻; Ksp = 6.0 × 10⁻³⁶

Qsp = [Cu²⁺][S²⁻] = (0.10)(1.0 × 10⁻¹⁹) = 1.0 × 10⁻²⁰

Qsp > Ksp, so a precipitate of CuS will form.

(b) PbS

PbS ⇌ Pb²⁺ + S²⁻; Ksp = 2.5 × 10⁻²⁷

Qsp = [Pb²⁺][S²⁻] = (0.10)(1.0 × 10⁻¹⁹) = 1.0 × 10⁻²⁰

Qsp > Ksp, so a precipitate of PbS will form.

(iii) NiS

NiS ⇌ Ni²⁺ + S²⁻; Ksp = 3.0 × 10⁻¹⁹

Qsp = [Ni²⁺][S²⁻] = (0.10)(1.0 × 10⁻¹⁹) = 1.0 × 10⁻²⁰

Qsp < Ksp, so a precipitate will not form.

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The weight of a sack potato in india is 50kgf. will the weight increase or decrease in bhutan. why​
AfilCa [17]

Answer:

Assume that the sack was initially close to the sea level. Its weight will increase even though its mass stays the same.

Explanation:

The weight of an object typically refers to the size of the planet's gravitational attraction (a force) on this object. That's not the same as the mass of the object. The weight of an object at a position depends on the size of the gravitational field there; on the other hand, the mass of the object is supposed to be same regardless of the location- as long as the object stays intact.

Let g denote the strength of the gravitational field at a certain point. If the mass of an object is m, its weight at that point will be m \cdot g.

Indeed, g \approx 9.81\; \rm N \cdot kg^{-1} on many places of the earth. However, this value is accurate only near the sea level. The equation for universal gravitation is a more general way for finding the strength of the gravitational field at an arbitrary height. Let G denote the constant of universal gravitation, and let M denote the mass of the earth. At a distance r from the center of the earth (where

\displaystyle g \approx \frac{G \cdot M}{r^2}.

The elevation of many places in Bhutan are significantly higher than that of many places in India. Therefore, a sack of potato in Bhutan will likely be further away from the center of the earth (larger r) compared to a sack of potato in India.

Note, that in the approximation, the value of g is (approximately, because the earth isn't perfectly spherical) inversely proportional to the distance from the center of the planet. The gravitational field strength

On the other hand, the weight of an object of fixed mass is proportional to the gravitational field strength. Therefore, the same bag of potatoes will have a smaller weight at most places in Bhutan compared to most places in India.

6 0
3 years ago
In the following equation, which element has been reduced?
Mila [183]
The answer is A. you sre correct!
4 0
3 years ago
g Write a molecular equation for the precipitation reaction that occurs (if any) when the following solutions are mixed. If no r
Mrac [35]

Answer:

CuBr₂(aq) + Pb(CH₃COO)₂(aq) → Cu(CH₃COO)₂(aq) + PbBr₂ (s)↓

Explanation:

We identify the reactants:

CuBr₂ and Pb(CH₃COO)₂

The products will be: Cu(CH₃COO)₂ and PbBr₂

You may know these information:

Salts from acetate are soluble.

Bromide can make solid salts with these cations: Ag⁺, Pb²⁺, Hg₂²⁺, Cu⁺

PbBr₂ is formed, so this will be our precipitate

The equation is:

CuBr₂(aq) + Pb(CH₃COO)₂(aq) → Cu(CH₃COO)₂(aq) + PbBr₂ (s)↓

8 0
3 years ago
Reading the above graph to the nearest tenth of a milliliter, what is the volume of sodium hydroxide at the equivalence point?
Vlada [557]

Answer:

The volume of sodium hydroxide at the equivalence point is:

  • <u>14.9 mL of sodium hydroxide</u>.

Explanation:

<u>The equivalence point occurs when, in this case, the HCl is completely neutralized with the solution of NaOH, how you can see this doesn't occur in the last point but occurs in the nineteenth point, where the pH is no more acid (below to 7) but is 11 approximately</u>, then you must see in the X-axis from this point and you can see the volume is almost 15, by this reason I calculate the valor of 14.9 milliliters.

7 0
3 years ago
Balance the following reaction. A coefficient of "1" is understood. Choose option "blank" for the correct answer if the coeffici
arlik [135]

The given reaction is:

C4H10 + O2 → CO2 + H2O

The above equation is not balanced due to the unequal distribution of atoms on either side of equation

# atoms Reactants           # atoms products

C = 4                                    C = 1

H = 10                                  H = 2

O = 2                                   O = 3

In order to balance it, multiply C4H10 by 2, O2 by 13, CO2 by 8 and H2O by 10 to get:

2C4H10 + 13 O2 → 8CO2 + 10H2O

7 0
3 years ago
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