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White raven [17]

2 years ago

5

Colin is helping the librarian return books

1 answer:

DedPeter [7]2 years ago

6 0

Explanation:

You mean the librarian is helping colin return books

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Without using Appendix B, predict the sign of ΔS° for(b) KBr(s)→ KBr(aq)

Volgvan

Since the sign is positive, the entropy increased by 88.48 J/K.

Examine the phases of the species present to determine whether a physical or chemical process will cause an increase or decrease in entropy. Keep in mind "Silly Little Goats" to aid you in telling.

[1 Sf K+1 + 1 Sf Br-1 (aq)] ([1Sf(KBr (s))])

[1(102.5) + 1(82.42)] - [1(96.44)] = 88.48 J/K

If the entropy has grown, we say that Delta S is positive, and if it has dropped, we say that Delta S is negative. Due to its ionic nature, KBr is soluble in water and causes the 'K(+)' ions to hydrate.

Learn more about Entropy here-

brainly.com/question/13146879

#SPJ4

8 0

2 years ago

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.8

Lubov Fominskaja [6]

Complete Question

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.82 when exactly 13 mL of base had been added, you notice that the concentration of the unknown acid was 0.1 M. What is the pKa of your unknown acid?

Answer:

The pK_a value is $pK_a =7.82$

Explanation:

From the question we are told

The volume of base is $V_B = 26.mL = 0.0260L$

The pH of solution is $pH = 7.82$

The concentration of the acid is $C_A = 0.1M$

From the pH we can see that the titration is between a strong base and a weak acid

Let assume that the the volume of acid is $V_A = 18mL= 0.018L$

Generally the concentration of base

$C_B = \frac{C_AV_A}{C_B}$

Substituting value

$C_B = \frac{0.1 * 0.01800}{0.0260}$

$C_B= 0.0692M$

When 13mL of the base is added a buffer is formed

The chemical equation of the reaction is

$HA_{(aq)} + OH^-_{(aq)} --------> A^{+}_{(aq)} + H_2 O_{(l)}$

Now before the reaction the number of mole of base is

$No \ of \ moles[N_B] = C_B * V_B$

Substituting value

$N_B = 0.01300 * 0.0692$

$= 0.0009 \ moles$

Now before the reaction the number of mole of acid is

$No \ of \ moles = C_B * V_B$

Substituting value

$N_A = 0.01800 *0.1$

$= 0.001800 \ moles$

Now after the reaction the number of moles of base is zero i.e has been used up

this mathematically represented as

$N_B ' = N_B - N_B = 0$

The number of moles of acid is

$N_A ' = N_A - N_B$

$= 0.0009\ moles$

The pH of this reaction can be mathematically represented as

$pH = pK_a + log \frac{[base]}{[acid]}$

Substituting values

$7.82 = pK_a +log \frac{0.0009}{0.0009}$

$pK_a =7.82$

8 0

3 years ago

What percent is tungsten made of from soil?

mars1129 [50]

I think i found your answers

4 0

3 years ago

a thermometer containing 8.3g of mercury has broken. if mercury ha a density of 13.6g/mL. what volume is spilled?

scoray [572]

D = m / V

13.6 = 8.3 / V

V = 8.3 / 13.6

V = 0.610 mL

hope this helps!

4 0

4 years ago

Read 2 more answers

If an object that stands 3 centimeters high is placed 12 centimeters in front of a plane mirror, how far from the mirror is the

ryzh [129]

Answer:

the mirror is 12 cm away from the image

Explanation:

; the image will be virtual and it will form at 12 cm distance behind the mirror.

7 0

3 years ago