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3 years ago

NaCl has a mc020-1.jpgHfus = 30.2 kJ/mol. What is the mass of a sample of NaCl that needs 732.6 kJ of heat to melt completely?

Chemistry

2 answers:

Sidana [21]3 years ago

8 0

Answer:

d.) 1417.7 on edge 2020

Explanation:

hope this helps!

lilavasa [31]3 years ago

5 0

Answer: The mass of the sample will be 1417.7 grams.

Explanation:

We are given:

$\Delta H_{fusion}=30.2kJ/mol$

This means that 1 mole of NaCl has an enthalpy of fusion of 30.2 kJ

1 mole of NaCl has a mass of 58.44 grams.

So, 30.2 kJ of heat is require for a mass 58.44 grams of NaCl

So, 732.6 kJ of heat will be required for = $\frac{58.44g}{30.2kJ}\times 732.6 kJ$ = 1417.65 grams of NaCl.

Hence, the mass of NaCl sample will be 1417.7 grams.

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vazorg [7]

Answer:

characteristics i believe

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3 years ago

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A chemist measures the amount of chlorine gas produced during an experiment. She finds that of chlorine gas is produced. Calcula

Trava [24]

Answer:

0.779 moles.

Explanation:

Mass of chlorine/number of moles = molar mass of chlorine.

Molar mass of chlorine = (35.5*2)

= 71 g/mol.

Mass = 55.3 g of chlorine.

Number of moles = 55.3/71

= 0.779 moles.

8 0

3 years ago

g On the basis of their respective pKa values, determine which is the stronger acid, acetic acid (pKa 5 4.7) or benzoic acid (ma

ozzi

Answer:

Benzoic acid is the stronger acid

Explanation:

Weak acids do not dissociate completely in the solution. They exists in equilibrium with their respective ions in the solution.

The extent of dissociation of the acid furnising hydrogen ions can be determined by using dissociation constant of acid ( $K_a$ ).

Thus for a weak acid, HA

$HA \rightleftharpoons A^- + H^+$

The $K_a$ is:

$K_a= \frac{[A^-][H^+]}{[HA]}$

The more the $K_a$ , the more the acid dissociates, the more the stronger is the acid.

Also,

$pK_a$ is defined as the negative logarithm of $K_a$ .

So, more the $pK_a$ , less is the $K_a$ and vice versa

All can be summed up as:

The less the value of $pK_a$ , the more the $K_a$ is and the more the acid dissociates and the more the stronger is the acid.

Given,

$pK_a$ of acetic acid = 54.7

$pK_a$ of benzoic acid = 54.2

$pK_a$ of benzoic acid < $pK_a$ of acetic acid

So, benzoic acid is the stronger acid.

5 0

3 years ago

For the reaction C2H4(g) + H2O(g) --> CH3CH2OH(g)

Dominik [7]

Answer : The value of equilibrium constant for this reaction at 262.0 K is $3.35\times 10^{2}$

Explanation :

As we know that,

$\Delta G^o=\Delta H^o-T\Delta S^o$

where,

$\Delta G^o$ = standard Gibbs free energy = ?

$\Delta H^o$ = standard enthalpy = -45.6 kJ = -45600 J

$\Delta S^o$ = standard entropy = -125.7 J/K

T = temperature of reaction = 262.0 K

Now put all the given values in the above formula, we get:

$\Delta G^o=(-45600J)-(262.0K\times -125.7J/K)$

$\Delta G^o=-12666.6J=-12.7kJ$

The relation between the equilibrium constant and standard Gibbs free energy is:

$\Delta G^o=-RT\times \ln k$

where,

$\Delta G^o$ = standard Gibbs free energy = -12666.6 J

R = gas constant = 8.314 J/K.mol

T = temperature = 262.0 K

K = equilibrium constant = ?

Now put all the given values in the above formula, we get:

$-12666.6J=-(8.314J/K.mol)\times (262.0K)\times \ln k$

$k=3.35\times 10^{2}$

Therefore, the value of equilibrium constant for this reaction at 262.0 K is $3.35\times 10^{2}$

3 0

4 years ago

What would be the final volume (in mL) of the aqueous potassium fluoride which was prepared by dissolving 8.0 g of potassium flu

andrew11 [14]

n=m/M

8.0g÷58.10g/mol=0.14mol

V=n/c

0.14mol÷0.89M=0.16L=1.6×10²mL

5 0

3 years ago