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Montano1993 [528]
1 year ago
15

A buffer is prepared by adding 150mL of 0.50 M NH3 to 250mL of 0.50 M NH4NO3. What is the pH of the final solution? (Kb for NH3

= 1.8 x 10^-5)
Chemistry
1 answer:
Juli2301 [7.4K]1 year ago
5 0

From the calculations, the pH of the final solution is 9.04.

<h3>What is the pH of the buffer?</h3>

We can use the Henderson Hasselbach equation to obtain the final pH of the solution in terms of the pKb and the base concentration.

Number of moles of salt = 250/1000 L * 0.5 M = 0.125 moles

Number of moles of base = 150/1000 L * 0.5 M = 0.075 moles

Total volume of solution = 250ml + 150ml = 400ml or 0.4 L

Molarity of base = 0.075 moles/ 0.4 L = 0.1875 M

Molarity of salt = 0.125 moles/ 0.4 L = 0.3125 M

pOH = pKb + log[salt/base]

pKb = -log(1.8 x 10^-5) = 4.74

pOH = 4.74 + log[0.3125/0.1875 ]

pOH = 4.96

pH = 14- 4.96

pH = 9.04

Learn more about pH:brainly.com/question/15289741

#SPJ1

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Explain why the total amount of energy does not decrease in an exergonic <br> chemical reaction
Zielflug [23.3K]

An exergonic reaction is a chemical reaction where the change in the free energy is negative (there is a net release of free energy),[1] indicating a spontaneous reaction. For processes that take place under constant pressure and temperature conditions, the Gibbs free energy is used whereas the Helmholtz energy is used for processes that take place under constant volume and temperature conditions.

Symbolically, the release of free energy, G, in an exergonic reaction (at constant pressure and temperature) is denoted as

{\displaystyle \Delta G=G_{\rm {products}}-G_{\rm {reactants}}<0.\,}

Although exergonic reactions are said to occur spontaneously, this does not imply that the reaction will take place at an observable rate. For instance, the disproportionation of hydrogen peroxide is very slow in the absence of a suitable catalyst. It has been suggested that eager would be a more intuitive term in this context.[2]

More generally, the terms exergonic and endergonic relate to the free energy change in any process, not just chemical reactions. An example of an exergonic reaction is cellular respiration. This relates to the degrees of freedom as a consequence of entropy, the temperature, and the difference in heat released or absorbed.

By contrast, the terms exothermic and endothermic relate to the overall exchange of heat during a process

4 0
3 years ago
rank the four gases (air, exhaled air, gas produced from the decomposition of H2O2, gas from decomposition of NaHCO3, in order o
SVEN [57.7K]

Answer: H₂O₂ (94%) > Air (23%) > Exhaled air (13%) > NaHCO₃ (0%)


Initial important note:


Although NaHCO₃ contents oxygen atoms, and you can calculate its compositoin, the resulting gas does not containg pure oxygen gas (O₂). For the comparisson it is not useful to calculate the content of oxygent atoms, but the concentration of O₂ gas. As such, the gas from NaHCO₃ contains 0% of pure O₂, that is why it is ranked last.


1) Air:


Source: internet


Approximate 23%. It is variable, because air is not a pure substance but a mixture of gases, whose compositon is not unique.


2) Exhaled air:


Source: internet.


Approximate 13%. The compositon of the air changes in our lungs, due to the respiration process: we inhale fresh air with around 23% of oxygen, part of this oxygen pass to the cells (lungs - blood - heart - cells) and then it is exhaled with a lower content of air and a greater content of CO₂


3) Air from the decomposition of H₂O₂.


In this case we can do a chemical calculation, since we can state the chemical equation of the reaction:


i) Chemical Equation:


H₂O₂ (g) → H₂ (g) + O₂ (g)


ii) mole ratio of the products 1 mol H₂ : 1 mol O₂


iii) convert moles into mass (grams)


1 mol H₂ × 2 × 1.008 g/mol = 2.016 g


1 mol O₂ × 2 × 15.999 g/mol = 31.998 g


Composition, % = [31.998 g / (2.016 g + 31.998 g) ] × 100 ≈ 94%



4) Air from the decomposition of NaHCO₃:


i) chemical equation:


2 NaHCO₃(s) → Na₂CO₃(s) + CO₂(g) + H₂O(g)


ii) mole ratio: take into account only the gases in the products:


1 mol CO₂ (g) : 1 mol H₂O


iii) mass in grams


CO₂: molar mass ia approximately 44.01 g/mol


H₂O: molar mass is approximately 18.02 g/mol


iii) Those gases although have oxygen atoms, do not hae free oxygen gas, which is what we are compariing. That means, that from the decomposition of NaHCO₃ you get 0% oxygen gas.


5) The result is:


H₂O₂ (94%) > Air (23%) > Exhaled air (13%) > NaHCO₃ (0%)

7 0
3 years ago
Read 2 more answers
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marin [14]

Answer:

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Explanation:

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7 0
2 years ago
When 1000 C of charge is passed through CuSO4 solution, x g of copper is deposited. How much charge should be passed through the
Stels [109]

Number of charge = 5018 C

<h3>Further explanation</h3>

Given

1000 C of charge for x grams of copper

Required

Number of charge

Solution

Faraday's Law :

\tt W=\dfrac{e.i.t}{96500}\\\\W=\dfrac{e.Q}{96500}

For 1000 C, W = x grams

\tt x=\dfrac{1000.e}{96500}=0.0104e

For 5x grams :

\tt 5x=\dfrac{e.Q}{96500}\\\\5\times 0.0104e=\dfrac{e.Q}{96500}\\\\Q=\dfrac{96500\times 5\times 0.0104e}{e}=5018~C

6 0
3 years ago
How many moles of CO2 are produced from the combustion of 5.25 moles of CH3OH?
iVinArrow [24]

First, we write the reaction for CH3OH combustion

CH3OH+3/2O2--->CO2+2H2O

for 1 mole of methanol, we get 1 mole of CO2, therefore for 5,25 moles of methanol we will get 5,25 moles of CO2

4 0
3 years ago
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