Based on the descriptions in the passage, which scientist proposed a model of the atom that matches the

A buffer consists of 0.120 M HNO2 and 0.150 M NaNO2 at 25°C. pka of HNO2 is 3.40. a. What is the pH of the buffer? b. What is th

Mashcka [7]

Explanation:

It is known that $K_{a}$ of $HNO_{2}$ = $4.5 \times 10^{-4}$ .

(a) Relation between $K_{a}$ and $pK_{a}$ is as follows.

$pK_{a} = -log (K_{a})$

Putting the values into the above formula as follows.

$pK_{a} = -log (K_{a})$

= $-log(4.5 \times 10^{-4})$

= 3.347

Also, relation between pH and $pK_{a}$ is as follows.

pH = $pK_{a} + log\frac{[conjugate base]}{[acid]}$

= $3.347+ log \frac{0.15}{0.12}$

= 3.44

Therefore, pH of the buffer is 3.44.

(b) No. of moles of HCl added = $Molarity \times volume$

= $11.6 M \times 0.001 L$

= 0.0116 mol

In the given reaction, $NO^{-}_{2}$ will react with $H^{+}$ to form $HNO_{2}$

Hence, before the reaction:

No. of moles of $NO^{-}_{2}$ = $0.15 M \times 1.0 L$

= 0.15 mol

And, no. of moles of $HNO_{2}$ = $0.12 M \times 1.0 L$

= 0.12 mol

On the other hand, after the reaction :

No. of moles of $NO^{-}_{2}$ = moles present initially - moles added

= (0.15 - 0.0116) mol

= 0.1384 mol

Moles of $HNO_{2}$ = moles present initially + moles added

= (0.12 + 0.0116) mol

= 0.1316 mol

As, $K_{a}$ = $4.5 \times 10^{-4}$

$pK_{a} = -log (K_{a})$

= $-log(4.5 \times 10^{-4})$

= 3.347

Since, volume is both in numerator and denominator, we can use mol instead of concentration.

As, pH = $pK_{a} + log \frac{[conjugate base]}{[acid]}$

= 3.347+ log {0.1384/0.1316}

= 3.369

= 3.37 (approx)

Thus, we can conclude that pH after the addition of 1.00 mL of 11.6 M HCl to 1.00 L of the buffer solution is 3.37.

6 0

3 years ago

Will you be my Magnesium, Silver, Nitrogen but "9.8m/s²" is silent? <br> Please help me here

zmey [24]

I don’t really understand but the symbols of these elements on the periodic table are

MgAgN

and 9.8 m/s^2 is the acceleration of gravity, commonly abbreviated as ‘g’

If you take out the ‘g’s from the periodic table equation(bc the question says 9.8m/s^2 is silent) it spells MAN

So the question could be “Will you be my man?”

4 0

2 years ago

What is true of a reaction that has reached equilibrium?

BabaBlast [244]

The correct option is A.

A chemical reaction is said to have reached an equilibrium stage if the rate of reaction of the forward reaction is equal to the rate of reaction of the reverse reaction. Two way arrows are usually used to depict equilibrium reactions. These arrows indicate that the chemical reaction can move both ways. At the equilibrium point the concentrations of both the reactants and the products are equal.

4 0

2 years ago

Read 2 more answers

Pulses A, B, C, and D all travel at 10 m/s on the same string but in opposite directions. The string is depicted at time t=0 in

Anit [1.1K]

(a) The displacement of point P at time t=0.10s is determined as +2cm.

(b) The displacement of point P at time t=0.20s is determined as -2cm.

<h3>What is displacement?</h3>

Displacement is the change in position of an object. It is obtained from the product of velocity and time of motion.

x = vt

<h3>Displacement of the waves after 0.1 s</h3>

x = 10 m/s x 0.1 s = 1 m

Each wave will travel 1 m to the right or to the left, depending on the initial direction.

wave B from left will stop at point 0 m
wave A from left will stop at point -1 m
wave C from right will stop at point 0 m
wave D from right will stop at point + 1 m

wave B and C superimposed and the displacement will be between A and D.

Amplitude of A = - 2cm

Amplitude of D = + 4cm

Displacement of point P = 4 cm - 2 cm = 2cm

<h3>Displacement of the waves after 0.2 s</h3>

x = 10 m/s x 0.1 s = 2 m

Each wave will travel 2 m to the right or to the left, depending on the initial direction.

wave B from left will stop at point 1 m
wave A from left will stop at point 0 m
wave C from right will stop at point -1 m
wave D from right will stop at point 0 m

Displacement of point P = (amplitude B + amplitude C) + (amplitude A + amplitude D)

Displacement of point P= (2cm - 2cm) + (2 cm - 4cm)= -2cm

Learn more about displacement here: brainly.com/question/2109763

#SPJ1

8 0

2 years ago

the specific heat capacity of water is 1 cal/gc how much heat in calories is released when 25.7 of water is cooled from 85 to 49

liraira [26]

Answer:

The amount of heat that is released is -925.2 cal

Explanation:

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is the amount of heat that a body can receive or release without affecting its molecular structure, that is, it does not change the state (solid, liquid, gaseous). In other words, sensible heat is the amount of heat that a body absorbs or releases without any changes in its physical state.

The equation that allows to calculate heat exchanges is:

Q = c * m * ΔT

Where Q is the heat exchanged by a body of mass m, constituted by a substance of specific heat c and where ΔT is the variation in temperature.

In this case:

c= 1 $\frac{cal}{g*C}$
m= 25.7 g
ΔT= Tfinal - Tinitial= 49 °C - 85 °C= -36 °C

Replacing:

Q= 1 $\frac{cal}{g*C}$ *25.7 g* (-36 C)

Solving:

Q= -925.2 cal

<u><em>The amount of heat that is released is -925.2 cal</em></u>

8 0

3 years ago