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faltersainse
1 month ago
6

In an experiment a student mixes a 50.0 mL sample of 0.100 M AgNO₃(aq) with a 50.0 mL sample of 0.100 M NaCl(aq) at 20.0°C in a

coffee-cup calorimeter.
What is the enthalpy change of the precipitation reaction represented above if the final temperature of the mixture is 21.0°C?
(Assume that the total mass of the mixture is 100. g and that the specific heat capacity of the mixture is 4.2 J/(g°C)).
Chemistry
1 answer:
KiRa [2.9K]1 month ago
5 0

The enthalpy change associated with the precipitation reaction is 84 kJ/mole

Why?

The chemical equation for the reaction can be written as

AgNO₃(aq) + NaCl (aq) → AgCl(s) + NaNO₃(aq)

To determine the enthalpy change, the following equation applies

\Delta H =\frac{Q}{n}

To calculate the heat (Q):

Q=m*C*\Delta T=(100g)*(4.2 J/g*^\circ C)*(21^\circ C-20^\circ C)\\\\Q=420J

Next, we need to calculate the number of moles involved in the reaction (n):

n=[AgNO_3]*v(L)=(0.1M)*(0.05L)=0.005moles

With these two values, we can substitute them into the first equation:

\Delta H= \frac{420J}{0.005moles}=84000J/mole=84kJ/mole

Have a great day!

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The standard cell potential (E°cell) for the reaction below is +0.63 V. The cell potential for this reaction is ________ V when
castortr0y [3046]

Answer: The cell potential for the given reaction stands at 0.50 V

Explanation:

The provided cell reaction is:

Pb^{2+}(aq)+Zn(s)\rightarrow Zn^{2+}(aq)+Pb(s)

The half-reactions are:

Anode oxidation half reaction:  Zn\rightarrow Zn^{2+}+2e^-

Cathode reduction half reaction:  Pb^{2+}+2e^-\rightarrow Pb

Initially, we need to find the cell potential for this reaction.

Utilizing the Nernst equation:

E_{cell}=E^o_{cell}-\frac{2.303RT}{nF}\log \frac{[Zn^{2+}]}{[Pb^{2+}]}

where,

F = Faraday's constant = 96500 C

R = gas constant = 8.314 J/mol·K

T = room temperature = 25^oC=273+25=298K

n = electrons exchanged in oxidation-reduction = 2

E^o_{cell} = standard electrode potential for the cell = +0.63 V

E_{cell} = cell potential for the reaction =?

[Zn^{2+}] = concentration of Zn²⁺ = 3.5 M

[Pb^{2+}] = 2.0\times 10^{-4}M

Now substituting all known values into the equation, we arrive at:

E_{cell}=(+0.63)-\frac{2.303\times (8.314)\times (298)}{2\times 96500}\log \frac{3.5}{2.0\times 10^{-4}}

E_{cell}=0.50V

So, the resulting cell potential for this reaction is 0.50 V

5 0
20 days ago
In the first order decomposition of acetone at 500°c, ch3och3→ productit is found that the concentration of acetone is 0.0300 m
lorasvet [2795]
For the first-order decomposition, the equation is: ln(x0 / x) = kt. At t = 200, x = 0.0300 M, we have ln(x0 / 0.03) = 200k. At t = 400, when x = 0.0200 M, we utilize ln(x0 / 0.02) = 400k. By multiplying the first equation by 2, we get 2ln(x0 / 0.03) = 400k, which aligns with the second equation, leading us to conclude that 2ln(x0 / 0.03) = ln(x0 / 0.02). This suggests (x0 / 0.03)^2 = x0 / 0.02, allowing us to find x0 = 0.045 M as the initial concentration. Plugging this back into the first equation yields: ln(0.045 / 0.03) = 200k, from which it follows that k = 0.0020273 (rate constant). The half-life can be calculated with x = 0.5x0: ln(x0 / 0.5x0) = 0.0020273t, resulting in ln(2) = 0.0020273t, which simplifies to t = 341.90 minutes (half-life).
5 0
26 days ago
Recording station x has determined that the epicenter of a recent earthquake was 250 km away. no information is available yet fr
alisha [2963]
The epicenter is determined to be located on a circle that is centered around Recording station X, with a radius extending 250 km.
7 0
26 days ago
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(58 g)/ (4L) reduce units to one
eduard [2782]
The result is 14.5 g L⁻¹. Here, the problem indicates to reduce the units to one. The existing units are g/L. To achieve a singular unit format, we can move L to the numerator, which can be executed as per the exponent laws; specifically, 1 / aˣ = a⁻ˣ. Thus, we can express 1 / L as L⁻¹. Consequently, the simplified unit remains g L⁻¹. However, remember to leave a space between two different units. This ultimately depicts a unit of density.
3 0
1 month ago
Identify the number of moles in 369 grams of calcium hydroxide. Use the periodic table and the polyatomic ion resource.
Alekssandra [3086]

Response: The moles in 369 grams of calcium hydroxide are 4.98 moles

Reasoning: Given,

Mass of calcium hydroxide = 369 g

Molar mass of calcium hydroxide = 74.093 g/mole

Formula used:

\text{Moles of calcium hydroxide}=\frac{\text{Mass of calcium hydroxide}}{\text{Molar mass of calcium hydroxide}}

Now substituting the provided values into this formula, you will find the moles of calcium hydroxide.

\text{Moles of calcium hydroxide}=\frac{369g}{74.093g/mole}=4.98mole

Thus, the number of moles in 369 grams of calcium hydroxide is, 4.98 moles

7 0
25 days ago
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