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3 years ago

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A rock weighing 30.0 g is placed in a graduated cylinder displacing the volume from 22.3 mL to 27.6 mL. What is density of the r

ock in grams/cubic centimeter?

1 answer:

cupoosta [38]3 years ago

5 0

V'=v2-v1=27.6-22.3
density=mass/v'
ps: ml is the same as cubic cm

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Answer:

3. The temperatures of the two substances equalize.

Explanation:

As two objects at different temperatures are placed in contact, heat is transferred from the warmer to the cooler object until the temperature of the two objects be the same.

The amount of heat that is transferred from the warmer object is equal to the amount of heat that is transferred into the cooler object.

This is in agreement with the law of conservation of energy.
<em>So, the right choice is: 3. The temperatures of the two substances equalize. </em>

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Water molecules pull the sodium and chloride ions apart, breaking the ionic bond that held them together. After the salt compounds are pulled apart, the sodium and chloride atoms are surrounded by water molecules, as this diagram shows. Once this happens, the salt is dissolved, resulting in a homogeneous solution.

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As a cooking method, braising is valued for its A. ability to retain flavor. B. quickness and convenience. C. ability to create

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3 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 $V_A = 18mL= 0.018L$

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

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

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

$pK_a =7.82$

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When an ionic solid is added into a solvent, you can see that the ionic solid dissociates into its respective cations and anions

SVEN [57.7K]

The order of the steps, from first to last, is as follows based on the information in the question:

1. Salt is broken down into cations and anions.

2. Anion hydration.

3. Cation hydration.

4. Cations and anions that have been dissolved start to settle as a solid salt.

5. The rate of dissolution and recrystallization are equal.

Without hydration of the ions, the cation and anion cannot get separated. The three processes of ion dissociation, cation hydration, and anion hydration must all take place at once.

<h3>Why water is an effective solvent?</h3>

Water is a great solvent that can dissolve a wide variety of compounds due to its polarity and capacity to create hydrogen bonds.

Learn more about solvation here:

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