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2 years ago

A buffer solution is prepared by adding NH4Cl to a solution of NH3 (ammonia). what happens if NaOH is added?

Chemistry

1 answer:

mixer [17]2 years ago

6 0

Answer: The reaction proceeds in the backward direction.

Explanation:

A buffer is a solution that maintains the pH of the solution and resists any significant changes of pH on the addition of acid or alkali.

A buffer solution of $NH_4Cl\text{ and }NH_3$ is prepared. It is a basic buffer as it is formed by the combination of a weak base $(NH_3)$ and its conjugate acid $(NH_4Cl)$

When a strong base (NaOH) is added to this buffer solution, the ammonium ions releases hydrogen ion to the solution which then combines with the hydroxide ions to form water and ammonia in a solution. Thus, maintaining the pH of the buffer.

The given chemical equation follows:

$NH_3(aq)+H_2O(l)\rightleftharpoons NH_4^+(aq)+OH^-(aq)$

Hence, the reaction will proceed in the backward direction.

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Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data: C2H4(g) + 3 O2(g) --> 2CO2(g) + 2 H2O

Brums [2.3K]

Answer : The standard enthalpy of formation of ethylene is, 52.4 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The formation reaction of $C_2H_4$ will be,

$2C(s)+2H_2(g)\rightarrow C_2H_4(g)$ $\Delta H_{formation}=?$

The intermediate balanced chemical reaction will be,

(1) $C_2H_4(g)+3O_2(g)\rightarrow 2CO_2(g)+2H_2O(l)$ $\Delta H_1=-1411kJ$

(2) $C(s)+O_2(g)\rightarrow CO_2(g)$ $\Delta H_2=-393.5kJ$

(3) $H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l)$ $\Delta H_3=-285.8kJ$

Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equation, we get :

(1) $2CO_2(g)+2H_2O(l)\rightarrow C_2H_4(g)+3O_2(g)$ $\Delta H_1=+1411kJ$

(2) $2C(s)+2O_2(g)\rightarrow 2CO_2(g)$ $\Delta H_2=2\times (-393.5kJ)=-787kJ$

(3) $2H_2(g)+2O_2(g)\rightarrow 2H_2O(l)$ $\Delta H_3=2\times (-285.8kJ)=-571.6kJ$

The expression for enthalpy of formation of $C_2H_4$ will be,

$\Delta H_{formation}=\Delta H_1+\Delta H_2+\Delta H_3$

$\Delta H=(+1411kJ)+(-787kJ)+(-571.6kJ)$

$\Delta H=52.4kJ$

Therefore, the standard enthalpy of formation of ethylene is, 52.4 kJ

7 0

3 years ago

For every 1lb you lose do to sweating you should consume ___ oz of water.

sdas [7]

Answer:

For every pound lost, replace it with 16 to 20 ounces of fluid

4 0

2 years ago

2. As NH4OH is added to an HCl solution, the pH of the solution

chubhunter [2.5K]

Answer:

Explanation:

Nh4OH + HCL ---> NH4Cl + H3O

so ph decreases as H3O increases

and OH also decreases

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3 years ago

Read 2 more answers

Help please I really really need it now

postnew [5]

1. A 2. B 5. B this is all I know hope it helps

5 0

2 years ago

A student is instructed to make 1 L of a 2.0 M solution of CaCl2 using dry salt. How should he do this?

Pachacha [2.7K]

The student should follow following steps to make 1 L of 2.0 M CaCl₂.

1. First he should calculate the number of moles of 2.0 M CaCl₂ in 1 L solution.

Molarity of the solution = 2.0 M
Volume of solution which should be prepared = 1 L

Molarity = number of moles / volume of the solution

Hence, number of moles in 1 L = 2 mol

2. Find out the mass of dry CaCl₂ in 2 moles.

moles = mass / molar mass

Moles of CaCl₂ = 2 mol
Molar mass of CaCl₂ = 110.98 g/mol

Hence, mass of CaCl₂ = 2 mol x 110.98 g/mol
= 221.96 g

3. Weigh the mass accurately

4. Then take a cleaned and dry1 L volumetric flask and place a funnel top of it. Then carefully add the salt into the volumetric flask and finally wash the funnel and watch glass with de-ionized water. That water also should be added into the volumetric flask.

5. Then add some de-ionized water into the volumetric flask and swirl well until all salt are dissolved.

6. Then top up to mark of the volumetric flask carefully.

7. As the final step prepared solution should be labelled.

4 0

2 years ago